version 3.7

* NEWS: Record release date.

.prev-version

@@ -1 +1 @@
-3.6.90
+3.6.93

NEWS

@@ -1,13 +1,6 @@
 GNU Bison NEWS
 
-* Noteworthy changes in release 3.6.91 (2020-07-09) [beta]
+* Noteworthy changes in release 3.7 (2020-07-23) [stable]
-
-** Bug fixes
-
-  Portability issues.
-
-
-* Noteworthy changes in release 3.6.90 (2020-07-04) [beta]
 
 ** Deprecated features
 
@@ -25,35 +18,114 @@ GNU Bison NEWS
 
   Contributed by Vincent Imbimbo.
 
-  When given `--report=counterexamples` or `-Wcounterexamples`, bison will
+  When given `-Wcounterexamples`/`-Wcex`, bison will now output
-  now output counterexamples for conflicts in the grammar.  These are
+  counterexamples for conflicts.
-  strings in the grammar which can be parsed in two ways due to the
-  conflict.  For example:
 
-    Example              exp '+' exp • '/' exp
+**** Unifying Counterexamples
-    First derivation     exp ::=[ exp ::=[ exp '+' exp • ] '/' exp ]
-    Second derivation    exp ::=[ exp '+' exp ::=[ exp • '/' exp ] ]
 
-  When Bison is installed with text styling enabled, the example is actually
+  Unifying counterexamples are strings which can be parsed in two ways due
-  shown twice, with colors highlighting the ambiguity.
+  to the conflict.  For example on a grammar that contains the usual
+  "dangling else" ambiguity:
 
-  This is a shift/reduce conflict caused by none of the operators having
+    $ bison else.y
-  precedence, so the example can be parsed in the two ways shown.  When
+    else.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
-  bison cannot find an example that can be derived in two ways, it instead
+    else.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
-  generates two examples that are the same up until the dot:
 
-    First example        expr • ID $end
+    $ bison else.y -Wcex
-    First derivation     $accept ::=[ s ::=[ a ::=[ expr • ] ID ] $end ]
+    else.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
-    Second example       expr • ID ',' ID $end
+    else.y: warning: shift/reduce conflict on token "else" [-Wcounterexamples]
-    Second derivation    $accept ::=[ s ::=[ a ::=[ expr ::=[ expr • ID ',' ] ] ID ] $end ]
+      Example: "if" exp "then" "if" exp "then" exp • "else" exp
+      Shift derivation
+        exp
+        ↳ "if" exp "then" exp
+                          ↳ "if" exp "then" exp • "else" exp
+      Example: "if" exp "then" "if" exp "then" exp • "else" exp
+      Reduce derivation
+        exp
+        ↳ "if" exp "then" exp                     "else" exp
+                          ↳ "if" exp "then" exp •
+
+  When text styling is enabled, colors are used in the examples and the
+  derivations to highlight the structure of both analyses.  In this case,
+
+    "if" exp "then" [ "if" exp "then" exp • ] "else" exp
+
+  vs.
+
+    "if" exp "then" [ "if" exp "then" exp • "else" exp ]
+
+
+  The counterexamples are "focused", in two different ways.  First, they do
+  not clutter the output with all the derivations from the start symbol,
+  rather they start on the "conflicted nonterminal". They go straight to the
+  point.  Second, they don't "expand" nonterminal symbols uselessly.
+
+**** Nonunifying Counterexamples
+
+  In the case of the dangling else, Bison found an example that can be
+  parsed in two ways (therefore proving that the grammar is ambiguous).
+  When it cannot find such an example, it instead generates two examples
+  that are the same up until the dot:
+
+    $ bison foo.y
+    foo.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
+    foo.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
+    foo.y:4.4-7: warning: rule useless in parser due to conflicts [-Wother]
+        4 | a: expr
+          |    ^~~~
+
+    $ bison -Wcex foo.y
+    foo.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
+    foo.y: warning: shift/reduce conflict on token ID [-Wcounterexamples]
+      First example: expr • ID ',' ID $end
+      Shift derivation
+        $accept
+        ↳ s                      $end
+          ↳ a                 ID
+            ↳ expr
+              ↳ expr • ID ','
+      Second example: expr • ID $end
+      Reduce derivation
+        $accept
+        ↳ s             $end
+          ↳ a        ID
+            ↳ expr •
+    foo.y:4.4-7: warning: rule useless in parser due to conflicts [-Wother]
+        4 | a: expr
+          |    ^~~~
 
   In these cases, the parser usually doesn't have enough lookahead to
   differentiate the two given examples.
 
-  The counterexamples are "focused": in two different ways.  First, they do
+**** Reports
-  not clutter the output with all the derivations from the start symbol,
+
-  rather they start on the "conflicted nonterminal". They go straight to the
+  Counterexamples are also included in the report when given
-  point.  Second, they don't "expand" nonterminal symbols uselessly.
+  `--report=counterexamples`/`-rcex` (or `--report=all`), with more
+  technical details:
+
+    State 7
+
+      1 exp: "if" exp "then" exp •  [$end, "then", "else"]
+      2    | "if" exp "then" exp • "else" exp
+
+      "else"  shift, and go to state 8
+
+      "else"    [reduce using rule 1 (exp)]
+      $default  reduce using rule 1 (exp)
+
+      shift/reduce conflict on token "else":
+          1 exp: "if" exp "then" exp •
+          2 exp: "if" exp "then" exp • "else" exp
+        Example: "if" exp "then" "if" exp "then" exp • "else" exp
+        Shift derivation
+          exp
+          ↳ "if" exp "then" exp
+                            ↳ "if" exp "then" exp • "else" exp
+        Example: "if" exp "then" "if" exp "then" exp • "else" exp
+        Reduce derivation
+          exp
+          ↳ "if" exp "then" exp                     "else" exp
+                            ↳ "if" exp "then" exp •
 
 *** File prefix mapping
 
@@ -67,6 +139,11 @@ GNU Bison NEWS
 
 ** Changes
 
+*** Diagnostics
+
+  When text styling is enabled and the terminal supports it, the warnings
+  now include hyperlinks to the documentation.
+
 *** Relocatable installation
 
   When installed to be relocatable (via `configure --enable-relocatable`),
@@ -107,6 +184,18 @@ GNU Bison NEWS
   Now the parser state can be examined when parsing is finished.  The parser
   state is reset when starting a new parse.
 
+** Documentation
+
+*** Examples
+
+  The bistromathic demonstrates %param and how to quote sources in the error
+  messages:
+
+    > 123 456
+    1.5-7: syntax error: expected end of file or + or - or * or / or ^ before number
+        1 | 123 456
+          |     ^~~
+
 ** Bug fixes
 
 *** Include the generated header (yacc.c)
@@ -4372,7 +4461,7 @@ LocalWords:  yysymbol yytnamerr yyreport ctx ARGMAX yysyntax stderr LPAREN
 LocalWords:  symrec yypcontext TOKENMAX yyexpected YYEMPTY yypstate YYEOF
 LocalWords:  autocompletion bistromathic submessages Cayuela lexcalc hoc
 LocalWords:  yytoken YYUNDEF YYerror basename Automake's UTF ifdef ffile
-LocalWords:  gotos readline Imbimbo Wcounterexamples
+LocalWords:  gotos readline Imbimbo Wcounterexamples Wcex Nonunifying rcex
 
 Local Variables:
 ispell-dictionary: "american"

README-hacking.md

@@ -444,7 +444,7 @@ added the `[-Wother]` part to all the warnings).  Part of the update can be
 done with a crude tool: `build-aux/update-test`.
 
 Once you ran the test suite, and therefore have many `testsuite.log` files,
-run, from the source tree:
+run `make update-tests`.  Or, by hand, from the *source* tree:
 
     $ ./build-aux/update-test $build/tests/testsuite.dir/*/testsuite.log
 

THANKS

@@ -45,6 +45,7 @@ Csaba Raduly              [email protected]
 Dagobert Michelsen        [email protected]
 Daniel Frużyński          [email protected]
 Daniel Galloway           [email protected]
+Daniela Becker            [email protected]
 Daniel Hagerty            [email protected]
 David Barto               [email protected]
 David J. MacKenzie        [email protected]

TODO

@@ -36,8 +36,6 @@ Unless we play it dumb (little structure).
 - How about not evaluating incomplete lines when the text is not finished
   (as shells do).
 
-- Caret diagnostics
-
 ** Questions
 *** Java
 - Should i18n be part of the Lexer?  Currently it's a static method of

bootstrap.conf

@@ -44,7 +44,7 @@ gnulib_modules='
   realloc-posix
   relocatable-prog relocatable-script
   rename
-  spawn-pipe stdbool stpcpy strdup-posix strerror strverscmp
+  spawn-pipe stdbool stpcpy stpncpy strdup-posix strerror strverscmp
   timevar
   unicodeio unistd unistd-safer unlink unlocked-io
   update-copyright unsetenv verify

data/bison-default.css

@@ -49,6 +49,10 @@
 .cex-5   { color: orange; }
 .cex-6   { color: brown; }
 .cex-7   { color: mauve; }
+.cex-8   { color: #013220; } /* Dark green. */
+.cex-9   { color: #e75480; } /* Dark pink. */
+.cex-10  { color: cyan; }
+.cex-11  { color: orange; }
 
 /* Cex: derivation rewriting steps.  */
 .cex-step { font-style: italic; }

data/xslt/xml2text.xsl

@@ -52,7 +52,7 @@
   <xsl:if test="nonterminal[@usefulness='useless-in-grammar']">
     <xsl:text>Nonterminals useless in grammar&#10;&#10;</xsl:text>
     <xsl:for-each select="nonterminal[@usefulness='useless-in-grammar']">
-      <xsl:text>   </xsl:text>
+      <xsl:text>    </xsl:text>
       <xsl:value-of select="@name"/>
       <xsl:text>&#10;</xsl:text>
     </xsl:for-each>
@@ -65,7 +65,7 @@
     <xsl:text>Terminals unused in grammar&#10;&#10;</xsl:text>
     <xsl:for-each select="terminal[@usefulness='unused-in-grammar']">
       <xsl:sort select="@symbol-number" data-type="number"/>
-      <xsl:text>   </xsl:text>
+      <xsl:text>    </xsl:text>
       <xsl:value-of select="@name"/>
       <xsl:text>&#10;</xsl:text>
     </xsl:for-each>
@@ -136,6 +136,7 @@
 </xsl:template>
 
 <xsl:template match="terminal">
+  <xsl:text>    </xsl:text>
   <xsl:value-of select="@name"/>
   <xsl:call-template name="line-wrap">
     <xsl:with-param name="first-line-length">
@@ -148,6 +149,9 @@
     </xsl:with-param>
     <xsl:with-param name="line-length" select="66" />
     <xsl:with-param name="text">
+      <xsl:if test="string-length(@type) != 0">
+        <xsl:value-of select="concat(' &lt;', @type, '&gt;')"/>
+      </xsl:if>
       <xsl:value-of select="concat(' (', @token-number, ')')"/>
       <xsl:for-each select="key('bison:ruleByRhs', @name)">
         <xsl:value-of select="concat(' ', @number)"/>
@@ -157,14 +161,18 @@
 </xsl:template>
 
 <xsl:template match="nonterminal">
+  <xsl:text>    </xsl:text>
   <xsl:value-of select="@name"/>
+  <xsl:if test="string-length(@type) != 0">
+    <xsl:value-of select="concat(' &lt;', @type, '&gt;')"/>
+  </xsl:if>
   <xsl:value-of select="concat(' (', @symbol-number, ')')"/>
   <xsl:text>&#10;</xsl:text>
   <xsl:variable name="output">
     <xsl:call-template name="line-wrap">
       <xsl:with-param name="line-length" select="66" />
       <xsl:with-param name="text">
-        <xsl:text>    </xsl:text>
+        <xsl:text>        </xsl:text>
         <xsl:if test="key('bison:ruleByLhs', @name)">
           <xsl:text>on@left:</xsl:text>
           <xsl:for-each select="key('bison:ruleByLhs', @name)">
@@ -173,7 +181,7 @@
         </xsl:if>
         <xsl:if test="key('bison:ruleByRhs', @name)">
           <xsl:if test="key('bison:ruleByLhs', @name)">
-            <xsl:text>, </xsl:text>
+            <xsl:text>&#10;        </xsl:text>
           </xsl:if>
           <xsl:text>on@right:</xsl:text>
           <xsl:for-each select="key('bison:ruleByRhs', @name)">
@@ -348,11 +356,11 @@
   <!-- RHS -->
   <xsl:for-each select="rhs/*">
     <xsl:if test="position() = $dot + 1">
-      <xsl:text> .</xsl:text>
+      <xsl:text> •</xsl:text>
     </xsl:if>
     <xsl:apply-templates select="."/>
     <xsl:if test="position() = last() and position() = $dot">
-      <xsl:text> .</xsl:text>
+      <xsl:text> •</xsl:text>
     </xsl:if>
   </xsl:for-each>
   <xsl:if test="$lookaheads">

data/xslt/xml2xhtml.xsl

@@ -227,6 +227,7 @@
   <xsl:text>&#10;</xsl:text>
   <p class="pre">
     <xsl:call-template name="style-rule-set">
+      <xsl:with-param name="anchor" select="'true'" />
       <xsl:with-param
         name="rule-set" select="rules/rule[@usefulness!='useless-in-grammar']"
       />
@@ -238,9 +239,11 @@
 </xsl:template>
 
 <xsl:template name="style-rule-set">
+  <xsl:param name="anchor"/>
   <xsl:param name="rule-set"/>
   <xsl:for-each select="$rule-set">
     <xsl:apply-templates select=".">
+      <xsl:with-param name="anchor" select="$anchor"/>
       <xsl:with-param name="pad" select="'3'"/>
       <xsl:with-param name="prev-lhs">
         <xsl:if test="position()>1">
@@ -306,9 +309,10 @@
     <xsl:text> Terminals, with rules where they appear</xsl:text>
   </h3>
   <xsl:text>&#10;&#10;</xsl:text>
-  <p class="pre">
+  <ul>
+    <xsl:text>&#10;</xsl:text>
     <xsl:apply-templates select="terminal"/>
-  </p>
+  </ul>
   <xsl:text>&#10;&#10;</xsl:text>
 </xsl:template>
 
@@ -318,41 +322,64 @@
     <xsl:text> Nonterminals, with rules where they appear</xsl:text>
   </h3>
   <xsl:text>&#10;&#10;</xsl:text>
-  <p class="pre">
+  <ul>
+    <xsl:text>&#10;</xsl:text>
     <xsl:apply-templates
       select="nonterminal[@usefulness!='useless-in-grammar']"
     />
-  </p>
+  </ul>
 </xsl:template>
 
 <xsl:template match="terminal">
-  <b><xsl:value-of select="@name"/></b>
+  <xsl:text>  </xsl:text>
-  <xsl:value-of select="concat(' (', @token-number, ')')"/>
+  <li>
-  <xsl:for-each select="key('bison:ruleByRhs', @name)">
+    <b><xsl:value-of select="@name"/></b>
-    <xsl:apply-templates select="." mode="number-link"/>
+    <xsl:if test="string-length(@type) != 0">
-  </xsl:for-each>
+      <xsl:value-of select="concat(' &lt;', @type, '&gt;')"/>
+    </xsl:if>
+    <xsl:value-of select="concat(' (', @token-number, ')')"/>
+    <xsl:for-each select="key('bison:ruleByRhs', @name)">
+      <xsl:apply-templates select="." mode="number-link"/>
+    </xsl:for-each>
+  </li>
   <xsl:text>&#10;</xsl:text>
 </xsl:template>
 
 <xsl:template match="nonterminal">
-  <b><xsl:value-of select="@name"/></b>
+  <xsl:text>  </xsl:text>
-  <xsl:value-of select="concat(' (', @symbol-number, ')')"/>
+  <li>
-  <xsl:text>&#10;    </xsl:text>
+    <b><xsl:value-of select="@name"/></b>
-  <xsl:if test="key('bison:ruleByLhs', @name)">
+    <xsl:if test="string-length(@type) != 0">
-    <xsl:text>on left:</xsl:text>
+      <xsl:value-of select="concat(' &lt;', @type, '&gt;')"/>
-    <xsl:for-each select="key('bison:ruleByLhs', @name)">
-      <xsl:apply-templates select="." mode="number-link"/>
-    </xsl:for-each>
-  </xsl:if>
-  <xsl:if test="key('bison:ruleByRhs', @name)">
-    <xsl:if test="key('bison:ruleByLhs', @name)">
-      <xsl:text>&#10;    </xsl:text>
     </xsl:if>
-    <xsl:text>on right:</xsl:text>
+    <xsl:value-of select="concat(' (', @symbol-number, ')')"/>
-    <xsl:for-each select="key('bison:ruleByRhs', @name)">
+    <xsl:text>&#10;    </xsl:text>
-      <xsl:apply-templates select="." mode="number-link"/>
+    <ul>
-    </xsl:for-each>
+      <xsl:text>&#10;</xsl:text>
-  </xsl:if>
+      <xsl:if test="key('bison:ruleByLhs', @name)">
+        <xsl:text>      </xsl:text>
+        <li>
+          <xsl:text>on left:</xsl:text>
+          <xsl:for-each select="key('bison:ruleByLhs', @name)">
+            <xsl:apply-templates select="." mode="number-link"/>
+          </xsl:for-each>
+        </li>
+        <xsl:text>&#10;</xsl:text>
+      </xsl:if>
+      <xsl:if test="key('bison:ruleByRhs', @name)">
+        <xsl:text>      </xsl:text>
+        <li>
+          <xsl:text>on right:</xsl:text>
+          <xsl:for-each select="key('bison:ruleByRhs', @name)">
+            <xsl:apply-templates select="." mode="number-link"/>
+          </xsl:for-each>
+        </li>
+        <xsl:text>&#10;</xsl:text>
+      </xsl:if>
+    <xsl:text>    </xsl:text>
+    </ul>
+    <xsl:text>&#10;  </xsl:text>
+  </li>
   <xsl:text>&#10;</xsl:text>
 </xsl:template>
 
@@ -385,7 +412,7 @@
         <xsl:value-of select="concat('state_', @number)"/>
       </xsl:attribute>
     </a>
-    <xsl:text>state </xsl:text>
+    <xsl:text>State </xsl:text>
     <xsl:value-of select="@number"/>
   </h3>
   <xsl:text>&#10;&#10;</xsl:text>
@@ -464,7 +491,12 @@
   </xsl:apply-templates>
 </xsl:template>
 
+<!--
+anchor = 'true': define as an <a> anchor.
+itemset = 'true': show the items.
+ -->
 <xsl:template match="rule">
+  <xsl:param name="anchor"/>
   <xsl:param name="itemset"/>
   <xsl:param name="pad"/>
   <xsl:param name="prev-lhs"/>
@@ -475,17 +507,21 @@
     <xsl:text>&#10;</xsl:text>
   </xsl:if>
 
-  <xsl:if test="$itemset != 'true'">
-    <a>
-      <xsl:attribute name="name">
-        <xsl:value-of select="concat('rule_', @number)"/>
-      </xsl:attribute>
-    </a>
-  </xsl:if>
   <xsl:text>  </xsl:text>
 
   <xsl:choose>
-    <xsl:when test="$itemset = 'true'">
+    <xsl:when test="$anchor = 'true'">
+      <a>
+        <xsl:attribute name="name">
+          <xsl:value-of select="concat('rule_', @number)"/>
+        </xsl:attribute>
+        <xsl:call-template name="lpad">
+          <xsl:with-param name="str" select="string(@number)"/>
+          <xsl:with-param name="pad" select="number($pad)"/>
+        </xsl:call-template>
+      </a>
+    </xsl:when>
+    <xsl:otherwise>
       <a>
         <xsl:attribute name="href">
           <xsl:value-of select="concat('#rule_', @number)"/>
@@ -495,25 +531,13 @@
           <xsl:with-param name="pad" select="number($pad)"/>
         </xsl:call-template>
       </a>
-    </xsl:when>
-    <xsl:otherwise>
-      <xsl:call-template name="lpad">
-        <xsl:with-param name="str" select="string(@number)"/>
-        <xsl:with-param name="pad" select="number($pad)"/>
-      </xsl:call-template>
     </xsl:otherwise>
   </xsl:choose>
   <xsl:text> </xsl:text>
 
   <!-- LHS -->
   <xsl:choose>
-    <xsl:when test="$itemset != 'true' and $prev-lhs = lhs[text()]">
+    <xsl:when test="$prev-lhs = lhs[text()]">
-      <xsl:call-template name="lpad">
-        <xsl:with-param name="str" select="'|'"/>
-        <xsl:with-param name="pad" select="number(string-length(lhs[text()])) + 2"/>
-      </xsl:call-template>
-    </xsl:when>
-    <xsl:when test="$itemset = 'true' and $prev-lhs = lhs[text()]">
       <xsl:call-template name="lpad">
         <xsl:with-param name="str" select="'|'"/>
         <xsl:with-param name="pad" select="number(string-length(lhs[text()])) + 2"/>

doc/bison.texi

@@ -263,7 +263,6 @@ Writing GLR Parsers
 * Merging GLR Parses::     Using GLR parsers to resolve ambiguities.
 * GLR Semantic Actions::   Considerations for semantic values and deferred actions.
 * Semantic Predicates::    Controlling a parse with arbitrary computations.
-* Compiler Requirements for GLR::  GLR parsers require a modern C compiler.
 
 Examples
 
@@ -943,7 +942,6 @@ on the resulting values to produce an arbitrary merged result.
 * Merging GLR Parses::     Using GLR parsers to resolve ambiguities.
 * GLR Semantic Actions::   Considerations for semantic values and deferred actions.
 * Semantic Predicates::    Controlling a parse with arbitrary computations.
-* Compiler Requirements for GLR::  GLR parsers require a modern C compiler.
 @end menu
 
 @node Simple GLR Parsers
@@ -1372,14 +1370,14 @@ widget:
 @noindent
 is one way to allow the same parser to handle two different syntaxes for
 widgets.  The clause preceded by @code{%?} is treated like an ordinary
-action, except that its text is treated as an expression and is always
+midrule action, except that its text is handled as an expression and is always
 evaluated immediately (even when in nondeterministic mode).  If the
 expression yields 0 (false), the clause is treated as a syntax error,
 which, in a nondeterministic parser, causes the stack in which it is reduced
-to die.  In a deterministic parser, it acts like YYERROR.
+to die.  In a deterministic parser, it acts like @code{YYERROR}.
 
 As the example shows, predicates otherwise look like semantic actions, and
-therefore you must be take them into account when determining the numbers
+therefore you must take them into account when determining the numbers
 to use for denoting the semantic values of right-hand side symbols.
 Predicate actions, however, have no defined value, and may not be given
 labels.
@@ -1393,7 +1391,7 @@ widget:
   @{ if (!new_syntax) YYERROR; @}
     "widget" id new_args  @{ $$ = f($3, $4); @}
 |  @{ if (new_syntax) YYERROR; @}
-    "widget" id old_args   @{ $$ = f($3, $4); @}
+    "widget" id old_args  @{ $$ = f($3, $4); @}
 ;
 @end example
 
@@ -1411,36 +1409,6 @@ reports an error.
 Finally, be careful in writing predicates: deferred actions have not been
 evaluated, so that using them in a predicate will have undefined effects.
 
-@node Compiler Requirements for GLR
-@subsection Considerations when Compiling GLR Parsers
-@cindex @code{inline}
-@cindex GLR parsers and @code{inline}
-
-The GLR parsers require a compiler for ISO C89 or
-later.  In addition, they use the @code{inline} keyword, which is not
-C89, but is C99 and is a common extension in pre-C99 compilers.  It is
-up to the user of these parsers to handle
-portability issues.  For instance, if using Autoconf and the Autoconf
-macro @code{AC_C_INLINE}, a mere
-
-@example
-%@{
-  #include <config.h>
-%@}
-@end example
-
-@noindent
-will suffice.  Otherwise, we suggest
-
-@example
-%@{
-  #if (__STDC_VERSION__ < 199901 && ! defined __GNUC__ \
-       && ! defined inline)
-  # define inline
-  #endif
-%@}
-@end example
-
 @node Locations
 @section Locations
 @cindex location
@@ -9921,10 +9889,11 @@ initially developed by Chinawat Isradisaikul and Andrew Myers
 As a first example, see the example grammar of @ref{Shift/Reduce}, which
 features on shift/reduce conflict:
 
+@c see doc/if-then-else.y
 @example
 $ @kbd{bison if-then-else.y}
-if-then-else.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
+if-then-else.y: @dwarning{warning}: 1 shift/reduce conflict [@dwarning{-Wconflicts-sr}]
-if-then-else.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+if-then-else.y: @dnotice{note}: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 @end example
 
 @noindent
@@ -9932,32 +9901,46 @@ Let's rerun @command{bison} with the option
 @option{-Wcex}/@option{-Wcounterexamples}@inlinefmt{info, (the following
 output is actually in color)}:
 
-@ifhtml
+@ifnottex
 @example
-Shift/reduce conflict on token "else":
+if-then-else.y: @dwarning{warning}: 1 shift/reduce conflict [@dwarning{-Wconflicts-sr}]
+if-then-else.y: @dwarning{warning}: shift/reduce conflict on token "else" [@dwarning{-Wcounterexamples}]
 @group
-  Example            @yellow{"if" expr "then"} @blue{"if" expr "then" stmt} @red{•} @yellow{"else" stmt}
+  Example: @yellow{"if" expr "then"} "if" expr "then" stmt • "else" stmt
-  First derivation   @yellow{if_stmt ::=[ "if" expr "then"} @green{stmt ::=[} @blue{if_stmt ::=[ "if" expr "then" stmt} @red{•} @blue{]} @green{]} @yellow{"else" stmt ]}
+  Shift derivation
-  Example            @yellow{"if" expr "then"} @blue{"if" expr "then" stmt} @red{•} @blue{"else" stmt}
+    @yellow{if_stmt}
-  Second derivation  @yellow{if_stmt ::=[ "if" expr "then"} @green{stmt ::=[} @blue{if_stmt ::=[ "if" expr "then" stmt} @red{•} @blue{"else" stmt ]} @green{]} @yellow{]}
+    @yellow{↳ "if" expr "then"} @green{stmt}
+                       @green{↳} @blue{if_stmt}
+                         @blue{↳ "if" expr "then" stmt} @red{•} @blue{"else" stmt}
+  Example: @yellow{"if" expr "then"} @blue{"if" expr "then" stmt} @red{•} @yellow{"else" stmt}
+  Reduce derivation
+    @yellow{if_stmt}
+    @yellow{↳ "if" expr "then"} @green{stmt}                        @yellow{"else" stmt}
+                       @green{↳} @blue{if_stmt}
+                         @blue{↳ "if" expr "then" stmt} @red{•}
 @end group
 @end example
-@end ifhtml
+@end ifnottex
-@ifnothtml
+@iftex
-@smallexample
+@example
-Shift/reduce conflict on token "else":
+if-then-else.y: @dwarning{warning}: 1 shift/reduce conflict [@dwarning{-Wconflicts-sr}]
+if-then-else.y: @dwarning{warning}: shift/reduce conflict on token "else" [@dwarning{-Wcounterexamples}]
 @group
-  Example
+  Example: @yellow{"if" expr "then"} "if" expr "then" stmt • "else" stmt
-    @yellow{"if" expr "then"} @blue{"if" expr "then" stmt} @red{•} @yellow{"else" stmt}
+  Shift derivation
-  First derivation
+    @yellow{if_stmt}
-    @yellow{if_stmt ::=[ "if" expr "then"} @green{stmt ::=[} @blue{if_stmt ::=[ "if" expr "then" stmt} @red{•} @blue{]} @green{]} @yellow{"else" stmt ]}
+    @yellow{@arrow{} "if" expr "then"} @green{stmt}
-  Example
+                        @green{@arrow{}} @blue{if_stmt}
-    @yellow{"if" expr "then"} @blue{"if" expr "then" stmt} @red{•} @blue{"else" stmt}
+                          @blue{@arrow{} "if" expr "then" stmt} @red{•} @blue{"else" stmt}
-  Second derivation
+  Example: @yellow{"if" expr "then"} @blue{"if" expr "then" stmt} @red{•} @yellow{"else" stmt}
-    @yellow{if_stmt ::=[ "if" expr "then"} @green{stmt ::=[} @blue{if_stmt ::=[ "if" expr "then" stmt} @red{•} @blue{"else" stmt ]} @green{]} @yellow{]}
+  Reduce derivation
+    @yellow{if_stmt}
+    @yellow{@arrow{} "if" expr "then"} @green{stmt}                        @yellow{"else" stmt}
+                        @green{@arrow{}} @blue{if_stmt}
+                           @blue{@arrow{} "if" expr "then" stmt} @red{•}
 @end group
-@end smallexample
+@end example
-@end ifnothtml
+@end iftex
 
 This shows two different derivations for one single expression.  That
 demonstrates that the grammar is ambiguous.
@@ -9967,6 +9950,7 @@ demonstrates that the grammar is ambiguous.
 As a more delicate example, consider the example grammar of
 @ref{Reduce/Reduce}, which features a reduce/reduce conflict:
 
+@c doc/sequence.y
 @example
 %%
 sequence:
@@ -9982,32 +9966,112 @@ maybeword:
 
 Bison generates the following counterexamples:
 
+@ifnottex
 @example
+@group
 $ @kbd{bison -Wcex sequence.y}
 sequence.y: @dwarning{warning}: 1 shift/reduce conflict [@dwarning{-Wconflicts-sr}]
 sequence.y: @dwarning{warning}: 2 reduce/reduce conflicts [@dwarning{-Wconflicts-rr}]
-Shift/reduce conflict on token "word":
+@end group
-  Example              @red{•} @yellow{"word"}
+@group
-  First derivation     @yellow{sequence ::=[} @green{sequence ::=[} @red{•} @green{]} @yellow{"word" ]}
+sequence.y: @dwarning{warning}: shift/reduce conflict on token "word" [@dwarning{-Wcounterexamples}]
-  Example              @red{•} @green{"word"}
+  Example: @red{•} @green{"word"}
-  Second derivation    @yellow{sequence ::=[} @green{maybeword ::=[} @red{•} @green{"word" ]} @yellow{]}
+  Shift derivation
-
+    @yellow{sequence}
-Reduce/reduce conflict on tokens $end, "word":
+    @yellow{↳} @green{maybeword}
-  Example              @red{•}
+      @green{↳} @red{•} @green{"word"}
-  First derivation     @yellow{sequence ::=[} @red{•} @yellow{]}
+  Example: @red{•} @yellow{"word"}
-  Example              @red{•}
+  Reduce derivation
-  Second derivation    @yellow{sequence ::=[} @green{maybeword ::=[} @red{•} @green{]} @yellow{]}
+    @yellow{sequence}
-
+    @yellow{↳} @green{sequence} @yellow{"word"}
-Shift/reduce conflict on token "word":
+      @green{↳} @red{•}
-  Example              @red{•} @yellow{"word"}
+@end group
-  First derivation     @yellow{sequence ::=[} @green{sequence ::=[} @blue{maybeword ::=[} @red{•} @blue{]} @green{]} @yellow{"word" ]}
+@group
-  Example              @red{•} @green{"word"}
+sequence.y: @dwarning{warning}: reduce/reduce conflict on tokens $end, "word" [@dwarning{-Wcounterexamples}]
-  Second derivation    @yellow{sequence ::=[} @green{maybeword ::=[} @red{•} @green{"word" ]} @yellow{]}
+  Example: @red{•}
-
+  First reduce derivation
+    @yellow{sequence}
+    @yellow{↳} @red{•}
+  Example: @red{•}
+  Second reduce derivation
+    @yellow{sequence}
+    @yellow{↳} @green{maybeword}
+      @green{↳} @red{•}
+@end group
+@group
+sequence.y: @dwarning{warning}: shift/reduce conflict on token "word" [@dwarning{-Wcounterexamples}]
+  Example: @red{•} @green{"word"}
+  Shift derivation
+    @yellow{sequence}
+    @yellow{↳} @green{maybeword}
+      @green{↳} @red{•} @green{"word"}
+  Example: @red{•} @yellow{"word"}
+  Reduce derivation
+    @yellow{sequence}
+    @yellow{↳} @green{sequence}    @yellow{"word"}
+      @green{↳} @blue{maybeword}
+        @blue{↳} @red{•}
+@end group
+@group
 sequence.y:8.3-45: @dwarning{warning}: rule useless in parser due to conflicts [@dwarning{-Wother}]
     8 |   @dwarning{%empty    @{ printf ("empty maybeword\n"); @}}
       |   @dwarning{^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~}
+@end group
 @end example
+@end ifnottex
+@iftex
+@example
+@group
+$ @kbd{bison -Wcex sequence.y}
+sequence.y: @dwarning{warning}: 1 shift/reduce conflict [@dwarning{-Wconflicts-sr}]
+sequence.y: @dwarning{warning}: 2 reduce/reduce conflicts [@dwarning{-Wconflicts-rr}]
+@end group
+@group
+sequence.y: @dwarning{warning}: shift/reduce conflict on token "word" [@dwarning{-Wcounterexamples}]
+  Example: @red{•} @green{"word"}
+  Shift derivation
+    @yellow{sequence}
+    @yellow{@arrow{}} @green{maybeword}
+       @green{@arrow{}} @red{•} @green{"word"}
+  Example: @red{•} @yellow{"word"}
+  Reduce derivation
+    @yellow{sequence}
+    @yellow{@arrow{}} @green{sequence} @yellow{"word"}
+       @green{@arrow{}} @red{•}
+@end group
+@group
+sequence.y: @dwarning{warning}: reduce/reduce conflict on tokens $end, "word" [@dwarning{-Wcounterexamples}]
+  Example: @red{•}
+  First reduce derivation
+    @yellow{sequence}
+    @yellow{@arrow{}} @red{•}
+  Example: @red{•}
+  Second reduce derivation
+    @yellow{sequence}
+    @yellow{@arrow{}} @green{maybeword}
+       @green{@arrow{}} @red{•}
+@end group
+@group
+sequence.y: @dwarning{warning}: shift/reduce conflict on token "word" [@dwarning{-Wcounterexamples}]
+  Example: @red{•} @green{"word"}
+  Shift derivation
+    @yellow{sequence}
+    @yellow{@arrow{}} @green{maybeword}
+       @green{@arrow{}} @red{•} @green{"word"}
+  Example: @red{•} @yellow{"word"}
+  Reduce derivation
+    @yellow{sequence}
+    @yellow{@arrow{}} @green{sequence}    @yellow{"word"}
+      @green{@arrow{}} @blue{maybeword}
+         @blue{@arrow{}} @red{•}
+@end group
+@group
+sequence.y:8.3-45: @dwarning{warning}: rule useless in parser due to conflicts [@dwarning{-Wother}]
+    8 |   @dwarning{%empty    @{ printf ("empty maybeword\n"); @}}
+      |   @dwarning{^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~}
+@end group
+@end example
+@end iftex
 
 Each of these three conflicts, again, prove that the grammar is ambiguous.
 For instance, the second conflict (the reduce/reduce one) shows that the
@@ -10021,6 +10085,7 @@ that are the same up until the dot.  Most notably, this will happen when
 your grammar requires a stronger parser (more lookahead, LR instead of
 LALR).  The following example isn't LR(1):
 
+@c doc/ids.y
 @example
 %token ID
 %%
@@ -10031,13 +10096,58 @@ expr: %empty | expr ID ','
 
 @command{bison} reports:
 
-@smallexample
+@ifnottex
-Shift/reduce conflict on token ID:
+@example
-  First example        @blue{expr} @red{•} @green{ID} @yellow{$end}
+ids.y: @dwarning{warning}: 1 shift/reduce conflict [@dwarning{-Wconflicts-sr}]
-  First derivation     @yellow{$accept ::=[} @green{s ::=[} @blue{a ::=[ expr} @red{•} @blue{]} @green{ID ]} @yellow{$end ]}
+ids.y: @dwarning{warning}: shift/reduce conflict on token ID [@dwarning{-Wcounterexamples}]
-  Second example       @purple{expr} @red{•} @purple{ID ','} @green{ID} @yellow{$end}
+@group
-  Second derivation    @yellow{$accept ::=[} @green{s ::=[} @blue{a ::=[} @purple{expr ::=[ expr} @red{•} @purple{ID ',' ]} @blue{]} @green{ID ]} @yellow{$end ]}
+  First example: @purple{expr} @red{•} @purple{ID ','} @green{ID} @yellow{$end}
-@end smallexample
+  Shift derivation
+    @yellow{$accept}
+    @yellow{↳} @green{s}                      @yellow{$end}
+      @green{↳} @blue{a}                 @green{ID}
+        @blue{↳} @purple{expr}
+          @purple{↳ expr} @red{•} @purple{ID ','}
+  Second example: @blue{expr} @red{•} @green{ID} @yellow{$end}
+  Reduce derivation
+    @yellow{$accept}
+    @yellow{↳} @green{s}             @yellow{$end}
+      @green{↳} @blue{a}        @green{ID}
+        @blue{↳ expr} @red{•}
+@end group
+@group
+ids.y:4.4-7: @dwarning{warning}: rule useless in parser due to conflicts [@dwarning{-Wother}]
+    4 | a: expr
+      |    ^~~~
+@end group
+@end example
+@end ifnottex
+@iftex
+@example
+ids.y: @dwarning{warning}: 1 shift/reduce conflict [@dwarning{-Wconflicts-sr}]
+ids.y: @dwarning{warning}: shift/reduce conflict on token ID [@dwarning{-Wcounterexamples}]
+@group
+  First example: @purple{expr} @red{•} @purple{ID ','} @green{ID} @yellow{$end}
+  Shift derivation
+    @yellow{$accept}
+    @yellow{@arrow{}} @green{s}                      @yellow{$end}
+       @green{@arrow{}} @blue{a}                 @green{ID}
+          @blue{@arrow{}} @purple{expr}
+             @purple{@arrow{} expr} @red{•} @purple{ID ','}
+  Second example: @blue{expr} @red{•} @green{ID} @yellow{$end}
+  Reduce derivation
+    @yellow{$accept}
+    @yellow{@arrow{}} @green{s}             @yellow{$end}
+       @green{@arrow{}} @blue{a}        @green{ID}
+          @blue{@arrow{} expr} @red{•}
+@end group
+@group
+ids.y:4.4-7: @dwarning{warning}: rule useless in parser due to conflicts [@dwarning{-Wother}]
+    4 | a: expr
+      |    ^~~~
+@end group
+@end example
+@end iftex
 
 This conflict is caused by the parser not having enough information to know
 the difference between these two examples.  The parser would need an
@@ -10073,6 +10183,7 @@ by default.  As a consequence, the verbose output file is called
 
 The following grammar file, @file{calc.y}, will be used in the sequel:
 
+@c doc/calc.y
 @example
 @group
 %union
@@ -10116,7 +10227,7 @@ calc.y:19.1-7: @dwarning{warning}: nonterminal useless in grammar: useless [@dwa
    19 | @dwarning{useless: STR;}
       | @dwarning{^~~~~~~}
 calc.y: @dwarning{warning}: 7 shift/reduce conflicts [@dwarning{-Wconflicts-sr}]
-calc.y: @dwarning{warning}: rerun with option '-Wcounterexamples' to generate conflict counterexamples [@dwarning{-Wother}]
+calc.y: @dnotice{note}: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 @end smallexample
 
 Going back to the calc example, when given @option{--report=state},
@@ -10428,15 +10539,44 @@ When given @option{--report=counterexamples}, @command{bison} will generate
 counterexamples within the report, augmented with the corresponding items
 (@pxref{Counterexamples}).
 
+@ifnottex
 @example
-Shift/reduce conflict on token '/':
+shift/reduce conflict on token '/':
     1 exp: exp '+' exp •
     4 exp: exp • '/' exp
-  Example              @green{exp '+' exp} @red{•} @yellow{'/' exp}
+@group
-  First derivation     @yellow{exp ::=[} @green{exp ::=[ exp '+' exp} @red{•} @green{]} @yellow{'/' exp ]}
+  Example: exp '+' exp • '/' exp
-  Example              @yellow{exp '+'} @green{exp} @red{•} @green{'/' exp}
+  Shift derivation
-  Second derivation    @yellow{exp ::=[ exp '+'} @green{exp ::=[ exp} @red{•} @green{'/' exp ]} @yellow{]}
+    exp
+    ↳ exp '+' exp
+              ↳ exp • '/' exp
+  Example: exp '+' exp • '/' exp
+  Reduce derivation
+    exp
+    ↳ exp             '/' exp
+      ↳ exp '+' exp •
+@end group
 @end example
+@end ifnottex
+@iftex
+@example
+shift/reduce conflict on token '/':
+    1 exp: exp '+' exp •
+    4 exp: exp • '/' exp
+@group
+  Example: exp '+' exp • '/' exp
+  Shift derivation
+    exp
+    @arrow{} exp '+' exp
+               @arrow{} exp • '/' exp
+  Example: exp '+' exp • '/' exp
+  Reduce derivation
+    exp
+    @arrow{} exp             '/' exp
+       @arrow{} exp '+' exp •
+@end group
+@end example
+@end iftex
 
 This shows two separate derivations in the grammar for the same @code{exp}:
 @samp{e1 + e2 / e3}.  The derivations show how your rules would parse the
@@ -11047,7 +11187,7 @@ The exit status of @command{bison} is:
 @item 0 (success)
 when there were no errors.  Warnings, which are diagnostics about dubious
 constructs, do not change the exit status, unless they are turned into
-errors (@pxref{-Werror,,@option{-Werror}}).
+errors (@pxref{Werror,,@option{-Werror}}).
 
 @item 1 (failure)
 when there were errors.  No file was generated (except the reports generated
@@ -11284,22 +11424,22 @@ Options controlling the diagnostics.
 Output warnings falling in @var{category}.  @var{category} can be one
 of:
 @table @code
-@item conflicts-sr
+@item @anchor{Wconflicts-sr}conflicts-sr
-@itemx conflicts-rr
+@itemx @anchor{Wconflicts-rr}conflicts-rr
 S/R and R/R conflicts.  These warnings are enabled by default.  However, if
 the @code{%expect} or @code{%expect-rr} directive is specified, an
 unexpected number of conflicts is an error, and an expected number of
 conflicts is not reported, so @option{-W} and @option{--warning} then have
 no effect on the conflict report.
 
-@item counterexamples
+@item @anchor{Wcounterexamples}counterexamples
 @itemx cex
 Provide counterexamples for conflicts.  @xref{Counterexamples}.
 Counterexamples take time to compute.  The option @option{-Wcex} should be
 used by the developer when working on the grammar; it hardly makes sense to
 use it in a CI.
 
-@item dangling-alias
+@item @anchor{Wdangling-alias}dangling-alias
 Report string literals that are not bound to a token symbol.
 
 String literals, which allow for better error messages, are (too) liberally
@@ -11345,16 +11485,16 @@ foo: "baz" @{@}
       |      @dwarning{^~~~~}
 @end example
 
-@item deprecated
+@item @anchor{Wdeprecated}deprecated
 Deprecated constructs whose support will be removed in future versions of
 Bison.
 
-@item empty-rule
+@item @anchor{Wempty-rule}empty-rule
 Empty rules without @code{%empty}.  @xref{Empty Rules}.  Disabled by
 default, but enabled by uses of @code{%empty}, unless
 @option{-Wno-empty-rule} was specified.
 
-@item midrule-values
+@item @anchor{Wmidrule-values}midrule-values
 Warn about midrule values that are set but not used within any of the actions
 of the parent rule.
 For example, warn about unused @code{$2} in:
@@ -11374,7 +11514,7 @@ These warnings are not enabled by default since they sometimes prove to
 be false alarms in existing grammars employing the Yacc constructs
 @code{$0} or @code{$-@var{n}} (where @var{n} is some positive integer).
 
-@item precedence
+@item @anchor{Wprecedence}precedence
 Useless precedence and associativity directives.  Disabled by default.
 
 Consider for instance the following grammar:
@@ -11435,20 +11575,21 @@ One would get the exact same parser with the following directives instead:
 @end group
 @end example
 
-@item yacc
+@item @anchor{Wyacc}yacc
 Incompatibilities with POSIX Yacc.
 
-@item other
+@item @anchor{Wother}other
 All warnings not categorized above.  These warnings are enabled by default.
 
 This category is provided merely for the sake of completeness.  Future
 releases of Bison may move warnings from this category to new, more specific
 categories.
 
-@item all
+@item @anchor{Wall}all
-All the warnings except @code{dangling-alias} and @code{yacc}.
+All the warnings except @code{counterexamples}, @code{dangling-alias} and
+@code{yacc}.
 
-@item none
+@item @anchor{Wnone}none
 Turn off all the warnings.
 
 @item error
@@ -11459,8 +11600,7 @@ A category can be turned off by prefixing its name with @samp{no-}.  For
 instance, @option{-Wno-yacc} will hide the warnings about
 POSIX Yacc incompatibilities.
 
-@item -Werror
+@item @anchor{Werror}-Werror
-@anchor{-Werror}
 Turn enabled warnings for every @var{category} into errors, unless they are
 explicitly disabled by @option{-Wno-error=@var{category}}.
 
@@ -14824,13 +14964,13 @@ Bison.  See the file @file{ABOUT-NLS} for more information.
 I can't build Bison because my C compiler is too old.
 @end quotation
 
-Except for GLR parsers (@pxref{Compiler Requirements for GLR}), the C
+Except for GLR parsers (which require C99), the C code that Bison generates
-code that Bison generates requires only C89 or later.  However, Bison
+requires only C89 or later.  However, Bison itself requires common C99
-itself requires common C99 features such as declarations after
+features such as declarations after statements.  Bison's @code{configure}
-statements.  Bison's @code{configure} script attempts to enable C99 (or
+script attempts to enable C99 (or later) support on compilers that default
-later) support on compilers that default to pre-C99.  If your compiler
+to pre-C99.  If your compiler lacks these C99 features entirely, GCC may
-lacks these C99 features entirely, GCC may well be a better choice; or
+well be a better choice; or you can try upgrading to your compiler's latest
-you can try upgrading to your compiler's latest version.
+version.
 
 @node Where can I find help?
 @section Where can I find help?
@@ -15887,7 +16027,7 @@ London, Department of Computer Science, TR-00-12 (December 2000).
 @c LocalWords: TokenKind Automake's rtti Wcounterexamples Chinawat PLDI
 @c LocalWords: Isradisaikul tcite pcite rgbGreen colorGreen rgbYellow Wcex
 @c LocalWords: colorYellow rgbRed colorRed rgbBlue colorBlue rgbPurple
-@c LocalWords: colorPurple ifhtml ifnothtml situ rcex
+@c LocalWords: colorPurple ifhtml ifnothtml situ rcex MERCHANTABILITY Wnone
 
 @c Local Variables:
 @c ispell-dictionary: "american"

doc/calc.y

@@ -0,0 +1,23 @@
+%union
+{
+  int ival;
+  const char *sval;
+}
+
+%token <ival> NUM
+%nterm <ival> exp
+%token <sval> STR
+%nterm <sval> useless
+
+%left '+' '-'
+%left '*'
+
+%%
+exp:
+  exp '+' exp
+| exp '-' exp
+| exp '*' exp
+| exp '/' exp
+| NUM
+;
+useless: STR;

doc/ids.y

@@ -0,0 +1,5 @@
+%token ID
+%%
+s: a ID
+a: expr
+expr: %empty | expr ID ','

doc/if-then-else.y

@@ -0,0 +1,13 @@
+%%
+stmt:
+  expr
+| if_stmt
+;
+
+if_stmt:
+  "if" expr "then" stmt
+| "if" expr "then" stmt "else" stmt
+;
+
+expr:
+  "identifier"

doc/sequence.y

@@ -0,0 +1,10 @@
+%%
+sequence:
+  %empty
+| maybeword
+| sequence "word"
+;
+maybeword:
+  %empty
+| "word"
+;

examples/c/README.md

@@ -53,7 +53,9 @@ push-parser model.
 This example demonstrates best practices when using Bison.
 - Its hand-written scanner tracks locations.
 - Its interface is pure.
-- It uses the `error` token to get error recovery.
+- It uses %params to pass user information to the parser and scanner.
+- Its scanner uses the `error` token to signal lexical errors and enter
+  error recovery.
 - Its interface is "incremental", well suited for interaction: it uses the
   push-parser API to feed the parser with the incoming tokens.
 - It features an interactive command line with completion based on the
@@ -62,6 +64,13 @@ This example demonstrates best practices when using Bison.
   messages.
 - It uses a custom syntax error with location, lookahead correction and
   token internationalization.
+- Error messages quote the source with squiggles that underline the error:
+```
+> 123 456
+1.5-7: syntax error: expected end of file or + or - or * or / or ^ before number
+    1 | 123 456
+      |     ^~~
+```
 - It supports debug traces with semantic values.
 - It uses named references instead of the traditional $1, $2, etc.
 

examples/c/bistromathic/README.md

@@ -2,7 +2,9 @@
 This example demonstrates best practices when using Bison.
 - Its hand-written scanner tracks locations.
 - Its interface is pure.
-- It uses the `error` token to get error recovery.
+- It uses %params to pass user information to the parser and scanner.
+- Its scanner uses the `error` token to signal lexical errors and enter
+  error recovery.
 - Its interface is "incremental", well suited for interaction: it uses the
   push-parser API to feed the parser with the incoming tokens.
 - It features an interactive command line with completion based on the
@@ -11,6 +13,13 @@ This example demonstrates best practices when using Bison.
   messages.
 - It uses a custom syntax error with location, lookahead correction and
   token internationalization.
+- Error messages quote the source with squiggles that underline the error:
+```
+> 123 456
+1.5-7: syntax error: expected end of file or + or - or * or / or ^ before number
+    1 | 123 456
+      |     ^~~
+```
 - It supports debug traces with semantic values.
 - It uses named references instead of the traditional $1, $2, etc.
 

examples/c/bistromathic/bistromathic.test

@@ -101,14 +101,28 @@ cat >input <<EOF
 EOF
 run 0 '> *
 > ''
-err: 1.1: syntax error: expected end of file or - or ( or exit or number or function etc., before *'
+err: 1.1: syntax error: expected end of file or - or ( or exit or number or function etc., before *
+err:     1 | *
+err:       | ^'
+
+# Underline long errors.
+cat >input <<EOF
+123 123456
+EOF
+run 0 '> 123 123456
+> ''
+err: 1.5-10: syntax error: expected end of file or + or - or * or / or ^ before number
+err:     1 | 123 123456
+err:       |     ^~~~~~'
 
 cat >input <<EOF
 1 + 2 * * 3
 EOF
 run 0 '> 1 + 2 * * 3
 > ''
-err: 1.9: syntax error: expected - or ( or number or function or variable before *'
+err: 1.9: syntax error: expected - or ( or number or function or variable before *
+err:     1 | 1 + 2 * * 3
+err:       |         ^'
 
 cat >input <<EOF
 1 / 0
@@ -132,8 +146,14 @@ run 0 '> ((1 ++ 2) ** 3)
 1332
 > ''
 err: 1.6: syntax error: expected - or ( or number or function or variable before +
+err:     1 | ((1 ++ 2) ** 3)
+err:       |      ^
 err: 2.5: syntax error: expected - or ( or number or function or variable before +
-err: 2.16: syntax error: expected - or ( or number or function or variable before *'
+err:     2 | (1 ++ 2) + (3 ** 4)
+err:       |     ^
+err: 2.16: syntax error: expected - or ( or number or function or variable before *
+err:     2 | (1 ++ 2) + (3 ** 4)
+err:       |                ^'
 
 # The rule "( error )" should work even if there are no tokens between "(" and ")".
 cat >input <<EOF
@@ -142,7 +162,9 @@ EOF
 run 0 '> ()
 666
 > ''
-err: 1.2: syntax error: expected - or ( or number or function or variable before )'
+err: 1.2: syntax error: expected - or ( or number or function or variable before )
+err:     1 | ()
+err:       |  ^'
 
 
 cat >input <<EOF
@@ -189,6 +211,8 @@ err: LAC: checking lookahead function: S5
 err: LAC: checking lookahead variable: S6
 err: LAC: checking lookahead NEG: Err
 err: 1.2: syntax error: expected - or ( or number or function or variable before +
+err:     1 | (+_)
+err:       |  ^
 err: LAC: initial context discarded due to error recovery
 err: Shifting token error (1.2: )
 err: Entering state 10
@@ -286,7 +310,9 @@ run 0 '> (1+
 (       -       atan    cos     exp     ln      number  sin     sqrt
 > (1+
 > ''
-err: 1.4: syntax error: expected - or ( or number or function or variable before end of file'
+err: 1.4: syntax error: expected - or ( or number or function or variable before end of file
+err:     1 | (1+
+err:       |    ^'
 
 # Check the completion of a word.
 sed -e 's/\\t/	/g' >input <<EOF
@@ -294,7 +320,9 @@ sed -e 's/\\t/	/g' >input <<EOF
 EOF
 run 0 '> (atan ( ''
 > ''
-err: 1.9: syntax error: expected - or ( or number or function or variable before end of file'
+err: 1.9: syntax error: expected - or ( or number or function or variable before end of file
+err:     1 | (atan ( ''
+err:       |         ^'
 
 # Check the completion at the very beginning.
 sed -e 's/\\t/	/g' >input <<EOF
@@ -313,8 +341,9 @@ sed -e 's/\\t/	/g' >input <<EOF
 EOF
 run -n 0 '> 1++ ''
 > ''
-err: 1.1: syntax error: expected - or ( or number or function or variable before +
 err: 1.3: syntax error: expected - or ( or number or function or variable before +
+err:     1 | 1++ ''
+err:       |   ^
 '
 
 # And even when the error was recovered from.
@@ -323,8 +352,10 @@ sed -e 's/\\t/	/g' >input <<EOF
 EOF
 run -n 0 '> (1++2) + 3 +  ''
 > ''
-err: 1.1: syntax error: expected - or ( or number or function or variable before +
-err: 1.1: syntax error: expected - or ( or number or function or variable before +
 err: 1.4: syntax error: expected - or ( or number or function or variable before +
+err:     1 | (1++2) + 3 +  ''
+err:       |    ^
 err: 1.15: syntax error: expected - or ( or number or function or variable before end of file
+err:     1 | (1++2) + 3 +  ''
+err:       |               ^
 '

examples/c/bistromathic/parse.y

@@ -65,6 +65,15 @@
 
   symrec *putsym (char const *name, int sym_type);
   symrec *getsym (char const *name);
+
+  // Exchanging information with the parser.
+  typedef struct
+  {
+    // Whether to not emit error messages.
+    int silent;
+    // The current input line.
+    const char *line;
+  } user_context;
 }
 
 // Emitted in the header file, after the definition of YYSTYPE.
@@ -74,9 +83,13 @@
 #   define __attribute__(Spec) /* empty */
 #  endif
 # endif
-  int yylex (const char **line, YYSTYPE *yylval, YYLTYPE *yylloc);
+
-  void yyerror (YYLTYPE *loc, char const *format, ...)
+  yytoken_kind_t
-    __attribute__ ((__format__ (__printf__, 2, 3)));
+  yylex (const char **line, YYSTYPE *yylval, YYLTYPE *yylloc,
+         const user_context *uctx);
+  void yyerror (YYLTYPE *loc, const user_context *uctx,
+                char const *format, ...)
+    __attribute__ ((__format__ (__printf__, 3, 4)));
 }
 
 // Emitted in the implementation file.
@@ -116,6 +129,9 @@
 // Generate the parser description file (calc.output).
 %verbose
 
+// User information exchanged with the parser and scanner.
+%param {const user_context *uctx}
+
 // Generate YYSTYPE from the types assigned to symbols.
 %define api.value.type union
 %token
@@ -171,7 +187,7 @@ exp:
   {
     if ($r == 0)
       {
-        yyerror (&@$, "error: division by zero");
+        yyerror (&@$, uctx, "error: division by zero");
         YYERROR;
       }
     else
@@ -257,8 +273,9 @@ symbol_count (void)
 | Scanner.  |
 `----------*/
 
-int
+yytoken_kind_t
-yylex (const char **line, YYSTYPE *yylval, YYLTYPE *yylloc)
+yylex (const char **line, YYSTYPE *yylval, YYLTYPE *yylloc,
+       const user_context *uctx)
 {
   int c;
 
@@ -328,7 +345,7 @@ yylex (const char **line, YYSTYPE *yylval, YYLTYPE *yylloc)
 
       // Stray characters.
     default:
-      yyerror (yylloc, "syntax error: invalid character: %c", c);
+      yyerror (yylloc, uctx, "syntax error: invalid character: %c", c);
       return TOK_YYerror;
     }
 }
@@ -366,8 +383,11 @@ error_format_string (int argc)
 
 
 int
-yyreport_syntax_error (const yypcontext_t *ctx)
+yyreport_syntax_error (const yypcontext_t *ctx, const user_context *uctx)
 {
+  if (uctx->silent)
+    return 0;
+
   enum { ARGS_MAX = 6 };
   yysymbol_kind_t arg[ARGS_MAX];
   int argsize = yypcontext_expected_tokens (ctx, arg, ARGS_MAX);
@@ -378,11 +398,12 @@ yyreport_syntax_error (const yypcontext_t *ctx)
     argsize = ARGS_MAX;
   const char *format = error_format_string (1 + argsize + too_many_expected_tokens);
 
+  const YYLTYPE *loc = yypcontext_location (ctx);
   while (*format)
     // %@: location.
     if (format[0] == '%' && format[1] == '@')
       {
-        YY_LOCATION_PRINT (stderr, *yypcontext_location (ctx));
+        YY_LOCATION_PRINT (stderr, *loc);
         format += 2;
       }
     // %u: unexpected token.
@@ -407,13 +428,25 @@ yyreport_syntax_error (const yypcontext_t *ctx)
         ++format;
       }
   fputc ('\n', stderr);
+
+  // Quote the source line.
+  {
+    fprintf (stderr, "%5d | %s\n", loc->first_line, uctx->line);
+    fprintf (stderr, "%5s | %*s", "", loc->first_column, "^");
+    for (int i = loc->last_column - loc->first_column - 1; 0 < i; --i)
+      putc ('~', stderr);
+    putc ('\n', stderr);
+  }
   return 0;
 }
 
 
 // Called by yyparse on error.
-void yyerror (YYLTYPE *loc, char const *format, ...)
+void yyerror (YYLTYPE *loc, const user_context *uctx, char const *format, ...)
 {
+  if (uctx->silent)
+    return;
+
   YY_LOCATION_PRINT (stderr, *loc);
   fputs (": ", stderr);
   va_list args;
@@ -449,11 +482,13 @@ xstrndup (const char *string, size_t n)
 static int
 process_line (YYLTYPE *lloc, const char *line)
 {
+  user_context uctx = {0, line};
   yypstate *ps = yypstate_new ();
   int status = 0;
   do {
     YYSTYPE lval;
-    status = yypush_parse (ps, yylex (&line, &lval, lloc), &lval, lloc);
+    yytoken_kind_t token = yylex (&line, &lval, lloc, &uctx);
+    status = yypush_parse (ps, token, &lval, lloc, &uctx);
   } while (status == YYPUSH_MORE);
   yypstate_delete (ps);
   lloc->last_line++;
@@ -468,18 +503,19 @@ expected_tokens (const char *input,
                  int *tokens, int ntokens)
 {
   YYDPRINTF ((stderr, "expected_tokens (\"%s\")", input));
+  user_context uctx = {1, input};
 
   // Parse the current state of the line.
   yypstate *ps = yypstate_new ();
   int status = 0;
+  YYLTYPE lloc = { 1, 1, 1, 1 };
   do {
-    YYLTYPE lloc = { 1, 1, 1, 1 };
     YYSTYPE lval;
-    int token = yylex (&input, &lval, &lloc);
+    yytoken_kind_t token = yylex (&input, &lval, &lloc, &uctx);
     // Don't let the parse know when we reach the end of input.
-    if (!token)
+    if (token == TOK_YYEOF)
       break;
-    status = yypush_parse (ps, token, &lval, &lloc);
+    status = yypush_parse (ps, token, &lval, &lloc, &uctx);
   } while (status == YYPUSH_MORE);
 
   int res = 0;

lib/.gitignore

@@ -313,6 +313,7 @@
 /stdlib.h
 /stdlib.in.h
 /stpcpy.c
+/stpncpy.c
 /strchrnul.c
 /strchrnul.valgrind
 /strdup.c

m4/.gitignore

@@ -175,6 +175,7 @@
 /stdio_h.m4
 /stdlib_h.m4
 /stpcpy.m4
+/stpncpy.m4
 /strchrnul.m4
 /strdup.m4
 /strerror.m4

src/AnnotationList.c

@@ -169,10 +169,10 @@ AnnotationList__compute_conflicted_tokens (bitset shift_tokens,
   bitset_copy (tokens, shift_tokens);
   for (int i = 0; i < reds->num; ++i)
     {
-      bitset_and (conflicted_tokens_rule, tokens, reds->lookahead_tokens[i]);
+      bitset_and (conflicted_tokens_rule, tokens, reds->lookaheads[i]);
       bitset_or (conflicted_tokens,
                  conflicted_tokens, conflicted_tokens_rule);
-      bitset_or (tokens, tokens, reds->lookahead_tokens[i]);
+      bitset_or (tokens, tokens, reds->lookaheads[i]);
       /* Check that rules are sorted on rule number or the next step in
          AnnotationList__compute_from_inadequacies will misbehave.  */
       aver (i == 0 || reds->rules[i-1] < reds->rules[i]);
@@ -401,7 +401,7 @@ AnnotationList__compute_from_inadequacies (
   struct obstack *annotations_obstackp,
   InadequacyListNodeCount *inadequacy_list_node_count)
 {
-  /* Return an empty list if s->lookahead_tokens = NULL.  */
+  /* Return an empty list if s->lookaheads = NULL.  */
   if (s->consistent)
     return;
 
@@ -422,7 +422,7 @@ AnnotationList__compute_from_inadequacies (
       /* Allocate the annotation node.  */
       {
         for (int rule_i = 0; rule_i < s->reductions->num; ++rule_i)
-          if (bitset_test (s->reductions->lookahead_tokens[rule_i],
+          if (bitset_test (s->reductions->lookaheads[rule_i],
                            conflicted_token))
             ++contribution_count;
         if (bitset_test (shift_tokens, conflicted_token))
@@ -445,7 +445,7 @@ AnnotationList__compute_from_inadequacies (
         for (int rule_i = 0; rule_i < s->reductions->num; ++rule_i)
           {
             rule *the_rule = s->reductions->rules[rule_i];
-            if (bitset_test (s->reductions->lookahead_tokens[rule_i],
+            if (bitset_test (s->reductions->lookaheads[rule_i],
                              conflicted_token))
               {
                 bitset_set (actions, rule_i);

src/complain.c

@@ -35,6 +35,13 @@
 #include "getargs.h"
 #include "quote.h"
 
+// The URL of the manual page about diagnostics.  Use the per-node
+// manual, to avoid downloading repeatedly the whole manual over the
+// Internet.
+static const char *diagnostics_url
+  = "https://www.gnu.org/software/bison/manual/html_node/Diagnostics.html";
+
+
 err_status complaint_status = status_none;
 
 bool warnings_are_errors = false;
@@ -96,6 +103,20 @@ end_use_class (const char *s, FILE *out)
     }
 }
 
+static void
+begin_hyperlink (FILE *out, const char *ref)
+{
+  if (out == stderr)
+    styled_ostream_set_hyperlink (errstream, ref, NULL);
+}
+
+static void
+end_hyperlink (FILE *out)
+{
+  if (out == stderr)
+    styled_ostream_set_hyperlink (errstream, NULL, NULL);
+}
+
 void
 flush (FILE *out)
 {
@@ -427,9 +448,20 @@ warnings_print_categories (warnings warn_flags, FILE *out)
         const char* style = severity_style (s);
         fputs (" [", out);
         begin_use_class (style, out);
-        fprintf (out, "-W%s%s",
+        // E.g., "counterexamples".
-                 s == severity_error ? "error=" : "",
+        const char *warning = argmatch_warning_argument (&w);
-                 argmatch_warning_argument (&w));
+        char ref[200];
+        snprintf (ref, sizeof ref,
+                  "%s#W%s", diagnostics_url, warning);
+        begin_hyperlink (out, ref);
+        ostream_printf (errstream,
+                        "-W%s%s",
+                        s == severity_error ? "error=" : "",
+                        warning);
+        end_hyperlink (out);
+        // Because we mix stdio with ostream I/O, we need to flush
+        // here for sake of color == debug.
+        flush (out);
         end_use_class (style, out);
         fputc (']', out);
         /* Display only the first match, the second is "-Wall".  */

src/conflicts.c

@@ -250,9 +250,9 @@ flush_shift (state *s, int token)
 `--------------------------------------------------------------------*/
 
 static void
-flush_reduce (bitset lookahead_tokens, int token)
+flush_reduce (bitset lookaheads, int token)
 {
-  bitset_reset (lookahead_tokens, token);
+  bitset_reset (lookaheads, token);
 }
 
 
@@ -275,10 +275,10 @@ resolve_sr_conflict (state *s, int ruleno, symbol **errors, int *nerrs)
   /* Find the rule to reduce by to get precedence of reduction.  */
   rule *redrule = reds->rules[ruleno];
   int redprec = redrule->prec->prec;
-  bitset lookahead_tokens = reds->lookahead_tokens[ruleno];
+  bitset lookaheads = reds->lookaheads[ruleno];
 
   for (symbol_number i = 0; i < ntokens; ++i)
-    if (bitset_test (lookahead_tokens, i)
+    if (bitset_test (lookaheads, i)
         && bitset_test (lookahead_set, i)
         && symbols[i]->content->prec)
       {
@@ -295,7 +295,7 @@ resolve_sr_conflict (state *s, int ruleno, symbol **errors, int *nerrs)
           {
             register_precedence (i, redrule->prec->number);
             log_resolution (redrule, i, shift_resolution);
-            flush_reduce (lookahead_tokens, i);
+            flush_reduce (lookaheads, i);
           }
         else
           /* Matching precedence levels.
@@ -316,7 +316,7 @@ resolve_sr_conflict (state *s, int ruleno, symbol **errors, int *nerrs)
             case right_assoc:
               register_assoc (i, redrule->prec->number);
               log_resolution (redrule, i, right_resolution);
-              flush_reduce (lookahead_tokens, i);
+              flush_reduce (lookaheads, i);
               break;
 
             case left_assoc:
@@ -329,7 +329,7 @@ resolve_sr_conflict (state *s, int ruleno, symbol **errors, int *nerrs)
               register_assoc (i, redrule->prec->number);
               log_resolution (redrule, i, nonassoc_resolution);
               flush_shift (s, i);
-              flush_reduce (lookahead_tokens, i);
+              flush_reduce (lookaheads, i);
               /* Record an explicit error for this token.  */
               errors[(*nerrs)++] = symbols[i];
               break;
@@ -369,7 +369,7 @@ set_conflicts (state *s, symbol **errors)
   for (int i = 0; i < reds->num; ++i)
     if (reds->rules[i]->prec
         && reds->rules[i]->prec->prec
-        && !bitset_disjoint_p (reds->lookahead_tokens[i], lookahead_set))
+        && !bitset_disjoint_p (reds->lookaheads[i], lookahead_set))
       resolve_sr_conflict (s, i, errors, &nerrs);
 
   if (nerrs)
@@ -385,13 +385,13 @@ set_conflicts (state *s, symbol **errors)
   /* Loop over all rules which require lookahead in this state.  Check
      for conflicts not resolved above.
 
-     reds->lookahead_tokens can be NULL if the LR type is LR(0).  */
+     reds->lookaheads can be NULL if the LR type is LR(0).  */
-  if (reds->lookahead_tokens)
+  if (reds->lookaheads)
     for (int i = 0; i < reds->num; ++i)
       {
-        if (!bitset_disjoint_p (reds->lookahead_tokens[i], lookahead_set))
+        if (!bitset_disjoint_p (reds->lookaheads[i], lookahead_set))
           conflicts[s->number] = true;
-        bitset_or (lookahead_set, lookahead_set, reds->lookahead_tokens[i]);
+        bitset_or (lookahead_set, lookahead_set, reds->lookaheads[i]);
       }
 }
 
@@ -460,7 +460,7 @@ count_state_sr_conflicts (const state *s)
   }
 
   for (int i = 0; i < reds->num; ++i)
-    bitset_or (lookahead_set, lookahead_set, reds->lookahead_tokens[i]);
+    bitset_or (lookahead_set, lookahead_set, reds->lookaheads[i]);
 
   bitset_and (lookahead_set, lookahead_set, shift_set);
 
@@ -499,7 +499,7 @@ count_state_rr_conflicts (const state *s)
     {
       int count = 0;
       for (int j = 0; j < reds->num; ++j)
-        count += bitset_test (reds->lookahead_tokens[j], i);
+        count += bitset_test (reds->lookaheads[j], i);
       if (2 <= count)
         res += count-1;
     }
@@ -534,7 +534,7 @@ count_rule_state_sr_conflicts (rule *r, state *s)
   for (int i = 0; i < reds->num; ++i)
     if (reds->rules[i] == r)
       {
-        bitset lookaheads = reds->lookahead_tokens[i];
+        bitset lookaheads = reds->lookaheads[i];
         int j;
         FOR_EACH_SHIFT (trans, j)
           res += bitset_test (lookaheads, TRANSITION_SYMBOL (trans, j));
@@ -576,8 +576,8 @@ count_rule_state_rr_conflicts (rule *r, state *s)
         if (reds->rules[j] != r)
           {
             bitset_and (lookaheads,
-                        reds->lookahead_tokens[i],
+                        reds->lookaheads[i],
-                        reds->lookahead_tokens[j]);
+                        reds->lookaheads[j]);
             res += bitset_count (lookaheads);
           }
   bitset_free (lookaheads);
@@ -686,7 +686,8 @@ conflicts_print (void)
       expected_rr_conflicts = -1;
     }
 
-  bool has_unexpected_conflicts = false;
+  // The warning flags used to emit a diagnostic, if we did.
+  warnings unexpected_conflicts_warning = Wnone;
   /* The following two blocks scream for factoring, but i18n support
      would make it ugly.  */
   {
@@ -703,7 +704,8 @@ conflicts_print (void)
             complain (NULL, complaint,
                       _("shift/reduce conflicts: %d found, %d expected"),
                       total, expected);
-            has_unexpected_conflicts = true;
+            if (total)
+              unexpected_conflicts_warning = complaint;
           }
       }
     else if (total)
@@ -713,7 +715,7 @@ conflicts_print (void)
                             "%d shift/reduce conflicts",
                             total),
                   total);
-        has_unexpected_conflicts = true;
+        unexpected_conflicts_warning = Wconflicts_sr;
       }
   }
 
@@ -731,7 +733,8 @@ conflicts_print (void)
             complain (NULL, complaint,
                       _("reduce/reduce conflicts: %d found, %d expected"),
                       total, expected);
-            has_unexpected_conflicts = true;
+            if (total)
+              unexpected_conflicts_warning = complaint;
           }
       }
     else if (total)
@@ -741,15 +744,16 @@ conflicts_print (void)
                             "%d reduce/reduce conflicts",
                             total),
                   total);
-        has_unexpected_conflicts = true;
+        unexpected_conflicts_warning = Wconflicts_rr;
       }
   }
 
   if (warning_is_enabled (Wcounterexamples))
     report_counterexamples ();
-  else if (has_unexpected_conflicts)
+  else if (unexpected_conflicts_warning != Wnone)
-    complain (NULL, Wother,
+    subcomplain (NULL, unexpected_conflicts_warning,
-              _("rerun with option '-Wcounterexamples' to generate conflict counterexamples"));
+                 _("rerun with option '-Wcounterexamples'"
+                   " to generate conflict counterexamples"));
 }
 
 void

src/counterexample.c

@@ -26,6 +26,7 @@
 #include <gl_linked_list.h>
 #include <gl_rbtreehash_list.h>
 #include <hash.h>
+#include <mbswidth.h>
 #include <stdlib.h>
 #include <textstyle.h>
 #include <time.h>
@@ -76,17 +77,29 @@ typedef struct
 {
   derivation *d1;
   derivation *d2;
+  bool shift_reduce;
   bool unifying;
   bool timeout;
 } counterexample;
 
 static counterexample *
 new_counterexample (derivation *d1, derivation *d2,
+                    bool shift_reduce,
                     bool u, bool t)
 {
-  counterexample *res = xmalloc (sizeof (counterexample));
+  counterexample *res = xmalloc (sizeof *res);
-  res->d1 = d1;
+  res->shift_reduce = shift_reduce;
-  res->d2 = d2;
+  if (shift_reduce)
+    {
+      // Display the shift first.
+      res->d1 = d2;
+      res->d2 = d1;
+    }
+  else
+    {
+      res->d1 = d1;
+      res->d2 = d2;
+    }
   res->unifying = u;
   res->timeout = t;
   return res;
@@ -100,14 +113,37 @@ free_counterexample (counterexample *cex)
   free (cex);
 }
 
-static void
+static int max (int a, int b)
-print_counterexample (counterexample *cex, FILE *out, const char *prefix)
 {
-  fprintf (out, "  %s%-20s ",
+  return a < b ? b : a;
-           prefix, cex->unifying ? _("Example") : _("First example"));
+}
-  derivation_print_leaves (cex->d1, out, prefix);
+
-  fprintf (out, "  %s%-20s ",
+static void
-           prefix, _("First derivation"));
+print_counterexample (const counterexample *cex, FILE *out, const char *prefix)
+{
+  const bool flat = getenv ("YYFLAT");
+  const char *example1_label
+    = cex->unifying ? _("Example") : _("First example");
+  const char *example2_label
+    = cex->unifying ? _("Example") : _("Second example");
+  const char *deriv1_label
+    = cex->shift_reduce ? _("Shift derivation") : _("First reduce derivation");
+  const char *deriv2_label
+    = cex->shift_reduce ? _("Reduce derivation") : _("Second reduce derivation");
+  const int width =
+    max (max (mbswidth (example1_label, 0), mbswidth (example2_label, 0)),
+         max (mbswidth (deriv1_label, 0),   mbswidth (deriv2_label, 0)));
+  if (flat)
+    fprintf (out, "  %s%s%*s ", prefix,
+             example1_label, width - mbswidth (example1_label, 0), "");
+  else
+    fprintf (out, "  %s%s: ", prefix, example1_label);
+  derivation_print_leaves (cex->d1, out);
+  if (flat)
+    fprintf (out, "  %s%s%*s ", prefix,
+             deriv1_label, width - mbswidth (deriv1_label, 0), "");
+  else
+    fprintf (out, "  %s%s", prefix, deriv1_label);
   derivation_print (cex->d1, out, prefix);
 
   // If we output to the terminal (via stderr) and we have color
@@ -115,15 +151,22 @@ print_counterexample (counterexample *cex, FILE *out, const char *prefix)
   // to see the differences.
   if (!cex->unifying || is_styled (stderr))
     {
-      fprintf (out, "  %s%-20s ",
+      if (flat)
-               prefix, cex->unifying ? _("Example") : _("Second example"));
+        fprintf (out, "  %s%s%*s ", prefix,
-      derivation_print_leaves (cex->d2, out, prefix);
+                 example2_label, width - mbswidth (example2_label, 0), "");
+      else
+        fprintf (out, "  %s%s: ", prefix, example2_label);
+      derivation_print_leaves (cex->d2, out);
     }
-  fprintf (out, "  %s%-20s ",
+  if (flat)
-           prefix, _("Second derivation"));
+    fprintf (out, "  %s%s%*s ", prefix,
+             deriv2_label, width - mbswidth (deriv2_label, 0), "");
+  else
+    fprintf (out, "  %s%s", prefix, deriv2_label);
   derivation_print (cex->d2, out, prefix);
 
-  fputc ('\n', out);
+  if (out != stderr)
+    putc ('\n', out);
 }
 
 /*
@@ -144,7 +187,7 @@ typedef struct si_bfs_node
 static si_bfs_node *
 si_bfs_new (state_item_number si, si_bfs_node *parent)
 {
-  si_bfs_node *res = xcalloc (1, sizeof (si_bfs_node));
+  si_bfs_node *res = xcalloc (1, sizeof *res);
   res->si = si;
   res->parent = parent;
   res->reference_count = 1;
@@ -175,6 +218,8 @@ si_bfs_free (si_bfs_node *n)
     }
 }
 
+typedef gl_list_t si_bfs_node_list;
+
 /**
  * start is a state_item such that conflict_sym is an element of FIRSTS of the
  * nonterminal after the dot in start. Because of this, we should be able to
@@ -188,15 +233,16 @@ expand_to_conflict (state_item_number start, symbol_number conflict_sym)
 {
   si_bfs_node *init = si_bfs_new (start, NULL);
 
-  gl_list_t queue = gl_list_create (GL_LINKED_LIST, NULL, NULL,
+  si_bfs_node_list queue
-                                    (gl_listelement_dispose_fn) si_bfs_free,
+    = gl_list_create (GL_LINKED_LIST, NULL, NULL,
-                                    true, 1, (const void **) &init);
+                      (gl_listelement_dispose_fn) si_bfs_free,
+                      true, 1, (const void **) &init);
   si_bfs_node *node = NULL;
   // breadth-first search for a path of productions to the conflict symbol
   while (gl_list_size (queue) > 0)
     {
       node = (si_bfs_node *) gl_list_get_at (queue, 0);
-      state_item *silast = state_items + node->si;
+      state_item *silast = &state_items[node->si];
       symbol_number sym = item_number_as_symbol_number (*silast->item);
       if (sym == conflict_sym)
         break;
@@ -238,7 +284,7 @@ expand_to_conflict (state_item_number start, symbol_number conflict_sym)
 
   for (si_bfs_node *n = node; n != NULL; n = n->parent)
     {
-      state_item *si = state_items + n->si;
+      state_item *si = &state_items[n->si];
       item_number *pos = si->item;
       if (SI_PRODUCTION (si))
         {
@@ -274,7 +320,7 @@ expand_to_conflict (state_item_number start, symbol_number conflict_sym)
  */
 static derivation *
 complete_diverging_example (symbol_number conflict_sym,
-                            gl_list_t path, derivation_list derivs)
+                            state_item_list path, derivation_list derivs)
 {
   // The idea is to transfer each pending symbol on the productions
   // associated with the given StateItems to the resulting derivation.
@@ -395,15 +441,15 @@ complete_diverging_example (symbol_number conflict_sym,
 /* Iterate backwards through the shifts of the path in the reduce
    conflict, and find a path of shifts from the shift conflict that
    goes through the same states. */
-static gl_list_t
+static state_item_list
-nonunifying_shift_path (gl_list_t reduce_path, state_item *shift_conflict)
+nonunifying_shift_path (state_item_list reduce_path, state_item *shift_conflict)
 {
   gl_list_node_t tmp = gl_list_add_last (reduce_path, NULL);
   gl_list_node_t next_node = gl_list_previous_node (reduce_path, tmp);
   gl_list_node_t node = gl_list_previous_node (reduce_path, next_node);
   gl_list_remove_node (reduce_path, tmp);
   state_item *si = shift_conflict;
-  gl_list_t result =
+  state_item_list result =
     gl_list_create_empty (GL_LINKED_LIST, NULL, NULL, NULL, true);
   // FIXME: bool paths_merged;
   for (; node != NULL; next_node = node,
@@ -425,10 +471,10 @@ nonunifying_shift_path (gl_list_t reduce_path, state_item *shift_conflict)
 
       // bfs to find a shift to the right state
       si_bfs_node *init = si_bfs_new (si - state_items, NULL);
-      gl_list_t queue =
+      si_bfs_node_list queue
-        gl_list_create (GL_LINKED_LIST, NULL, NULL,
+        = gl_list_create (GL_LINKED_LIST, NULL, NULL,
-                        (gl_listelement_dispose_fn) si_bfs_free,
+                          (gl_listelement_dispose_fn) si_bfs_free,
-                        true, 1, (const void **) &init);
+                          true, 1, (const void **) &init);
       si_bfs_node *sis = NULL;
       state_item *prevsi = NULL;
       while (gl_list_size (queue) > 0)
@@ -438,7 +484,7 @@ nonunifying_shift_path (gl_list_t reduce_path, state_item *shift_conflict)
           if (sis->si == 0)
             break;
 
-          state_item *search_si = state_items + sis->si;
+          state_item *search_si = &state_items[sis->si];
           // if the current state-item is a production item,
           // its reverse production items get added to the queue.
           // Otherwise, look for a reverse transition to the target state.
@@ -447,7 +493,7 @@ nonunifying_shift_path (gl_list_t reduce_path, state_item *shift_conflict)
           state_item_number sin;
           BITSET_FOR_EACH (biter, rsi, sin, 0)
             {
-              prevsi = state_items + sin;
+              prevsi = &state_items[sin];
               if (SI_TRANSITION (search_si))
                 {
                   if (prevsi->state == refsi->state)
@@ -465,9 +511,9 @@ nonunifying_shift_path (gl_list_t reduce_path, state_item *shift_conflict)
       // prepend path to shift we found
       if (sis)
         {
-          gl_list_node_t ln = gl_list_add_first (result, state_items + sis->si);
+          gl_list_node_t ln = gl_list_add_first (result, &state_items[sis->si]);
           for (si_bfs_node *n = sis->parent; n; n = n->parent)
-            ln = gl_list_add_after (result, ln, state_items + n->si);
+            ln = gl_list_add_after (result, ln, &state_items[n->si]);
 
         }
       si = prevsi;
@@ -493,17 +539,17 @@ nonunifying_shift_path (gl_list_t reduce_path, state_item *shift_conflict)
 static counterexample *
 example_from_path (bool shift_reduce,
                    state_item_number itm2,
-                   gl_list_t shortest_path, symbol_number next_sym)
+                   state_item_list shortest_path, symbol_number next_sym)
 {
   derivation *deriv1 =
     complete_diverging_example (next_sym, shortest_path, NULL);
-  gl_list_t path_2
+  state_item_list path_2
     = shift_reduce
     ? nonunifying_shift_path (shortest_path, &state_items [itm2])
     : shortest_path_from_start (itm2, next_sym);
   derivation *deriv2 = complete_diverging_example (next_sym, path_2, NULL);
   gl_list_free (path_2);
-  return new_counterexample (deriv1, deriv2, false, true);
+  return new_counterexample (deriv1, deriv2, shift_reduce, false, true);
 }
 
 /*
@@ -525,7 +571,7 @@ typedef struct
 static search_state *
 initial_search_state (state_item *conflict1, state_item *conflict2)
 {
-  search_state *res = xmalloc (sizeof (search_state));
+  search_state *res = xmalloc (sizeof *res);
   res->states[0] = new_parse_state (conflict1);
   res->states[1] = new_parse_state (conflict2);
   parse_state_retain (res->states[0]);
@@ -537,7 +583,7 @@ initial_search_state (state_item *conflict1, state_item *conflict2)
 static search_state *
 new_search_state (parse_state *ps1, parse_state *ps2, int complexity)
 {
-  search_state *res = xmalloc (sizeof (search_state));
+  search_state *res = xmalloc (sizeof *res);
   res->states[0] = ps1;
   res->states[1] = ps2;
   parse_state_retain (res->states[0]);
@@ -549,8 +595,8 @@ new_search_state (parse_state *ps1, parse_state *ps2, int complexity)
 static search_state *
 copy_search_state (search_state *parent)
 {
-  search_state *res = xmalloc (sizeof (search_state));
+  search_state *res = xmalloc (sizeof *res);
-  memcpy (res, parent, sizeof (search_state));
+  *res = *parent;
   parse_state_retain (res->states[0]);
   parse_state_retain (res->states[1]);
   return res;
@@ -583,6 +629,8 @@ search_state_print (search_state *ss)
   putc ('\n', stderr);
 }
 
+typedef gl_list_t search_state_list;
+
 static inline bool
 search_state_list_next (gl_list_iterator_t *it, search_state **ss)
 {
@@ -614,18 +662,20 @@ ss_set_parse_state (search_state *ss, int idx, parse_state *ps)
  */
 static counterexample *
 complete_diverging_examples (search_state *ss,
-                             symbol_number next_sym)
+                             symbol_number next_sym,
+                             bool shift_reduce)
 {
   derivation *new_derivs[2];
   for (int i = 0; i < 2; ++i)
     {
-      gl_list_t sitems;
+      state_item_list sitems;
       derivation_list derivs;
       parse_state_lists (ss->states[i], &sitems, &derivs);
       new_derivs[i] = complete_diverging_example (next_sym, sitems, derivs);
       gl_list_free (sitems);
     }
-  return new_counterexample (new_derivs[0], new_derivs[1], false, true);
+  return new_counterexample (new_derivs[0], new_derivs[1],
+                             shift_reduce, false, true);
 }
 
 /*
@@ -635,7 +685,7 @@ complete_diverging_examples (search_state *ss,
  */
 typedef struct
 {
-  gl_list_t states;
+  search_state_list states;
   int complexity;
 } search_state_bundle;
 
@@ -664,11 +714,13 @@ ssb_equals (const search_state_bundle *s1, const search_state_bundle *s2)
   return s1->complexity == s2->complexity;
 }
 
+typedef gl_list_t ssb_list;
+
 static size_t
-visited_hasher (const search_state *ss, size_t max)
+visited_hasher (const search_state *ss, size_t maximum)
 {
-  return (parse_state_hasher (ss->states[0], max)
+  return (parse_state_hasher (ss->states[0], maximum)
-          + parse_state_hasher (ss->states[1], max)) % max;
+          + parse_state_hasher (ss->states[1], maximum)) % maximum;
 }
 
 static bool
@@ -679,7 +731,7 @@ visited_comparator (const search_state *ss1, const search_state *ss2)
 }
 
 /* Priority queue for search states with minimal complexity. */
-static gl_list_t ssb_queue;
+static ssb_list ssb_queue;
 static Hash_table *visited;
 /* The set of parser states on the shortest lookahead-sensitive path. */
 static bitset scp_set = NULL;
@@ -702,7 +754,7 @@ ssb_append (search_state *ss)
   parse_state_free_contents_early (ss->states[1]);
   parse_state_retain (ss->states[0]);
   parse_state_retain (ss->states[1]);
-  search_state_bundle *ssb = xmalloc (sizeof (search_state_bundle));
+  search_state_bundle *ssb = xmalloc (sizeof *ssb);
   ssb->complexity = ss->complexity;
   gl_list_node_t n = gl_list_search (ssb_queue, ssb);
   if (!n)
@@ -756,12 +808,12 @@ reduction_cost (const parse_state *ps)
   return SHIFT_COST * shifts + PRODUCTION_COST * productions;
 }
 
-static gl_list_t
+static search_state_list
 reduction_step (search_state *ss, const item_number *conflict_item,
                 int parser_state, int rule_len)
 {
   (void) conflict_item; // FIXME: Unused
-  gl_list_t result =
+  search_state_list result =
     gl_list_create_empty (GL_LINKED_LIST, NULL, NULL, NULL, 1);
 
   parse_state *ps = ss->states[parser_state];
@@ -897,7 +949,7 @@ search_state_prepend (search_state *ss, symbol_number sym, bitset guide)
  * the same prefix up to the dot.
  */
 static bool
-has_common_prefix (const item_number *itm1, const item_number *itm2)
+have_common_prefix (const item_number *itm1, const item_number *itm2)
 {
   int i = 0;
   for (; !item_number_is_rule_number (itm1[i]); ++i)
@@ -988,14 +1040,14 @@ generate_next_states (search_state *ss, state_item *conflict1,
       // prepended further, reduce.
       if (ready1 && ready2)
         {
-          gl_list_t reduced1 = reduction_step (ss, conflict1->item, 0, len1);
+          search_state_list reduced1 = reduction_step (ss, conflict1->item, 0, len1);
           gl_list_add_last (reduced1, ss);
           search_state *red1 = NULL;
           for (gl_list_iterator_t iter = gl_list_iterator (reduced1);
                search_state_list_next (&iter, &red1);
                )
             {
-              gl_list_t reduced2 =
+              search_state_list reduced2 =
                 reduction_step (red1, conflict2->item, 1, len2);
               search_state *red2 = NULL;
               for (gl_list_iterator_t iter2 = gl_list_iterator (reduced2);
@@ -1011,7 +1063,7 @@ generate_next_states (search_state *ss, state_item *conflict1,
         }
       else if (ready1)
         {
-          gl_list_t reduced1 = reduction_step (ss, conflict1->item, 0, len1);
+          search_state_list reduced1 = reduction_step (ss, conflict1->item, 0, len1);
           search_state *red1 = NULL;
           for (gl_list_iterator_t iter = gl_list_iterator (reduced1);
                search_state_list_next (&iter, &red1);
@@ -1021,7 +1073,7 @@ generate_next_states (search_state *ss, state_item *conflict1,
         }
       else if (ready2)
         {
-          gl_list_t reduced2 = reduction_step (ss, conflict2->item, 1, len2);
+          search_state_list reduced2 = reduction_step (ss, conflict2->item, 1, len2);
           search_state *red2 = NULL;
           for (gl_list_iterator_t iter2 = gl_list_iterator (reduced2);
                search_state_list_next (&iter2, &red2);
@@ -1055,10 +1107,10 @@ static counterexample *
 unifying_example (state_item_number itm1,
                   state_item_number itm2,
                   bool shift_reduce,
-                  gl_list_t reduce_path, symbol_number next_sym)
+                  state_item_list reduce_path, symbol_number next_sym)
 {
-  state_item *conflict1 = state_items + itm1;
+  state_item *conflict1 = &state_items[itm1];
-  state_item *conflict2 = state_items + itm2;
+  state_item *conflict2 = &state_items[itm2];
   search_state *initial = initial_search_state (conflict1, conflict2);
   ssb_queue = gl_list_create_empty (GL_RBTREEHASH_LIST,
                                     (gl_listelement_equals_fn) ssb_equals,
@@ -1094,7 +1146,7 @@ unifying_example (state_item_number itm1,
               const state_item *si1src = parse_state_head (ps1);
               const state_item *si2src = parse_state_head (ps2);
               if (item_rule (si1src->item)->lhs == item_rule (si2src->item)->lhs
-                  && has_common_prefix (si1src->item, si2src->item))
+                  && have_common_prefix (si1src->item, si2src->item))
                 {
                   // Stage 4: both paths share a prefix
                   derivation *d1 = parse_state_derivation (ps1);
@@ -1104,7 +1156,7 @@ unifying_example (state_item_number itm1,
                     {
                       // Once we have two derivations for the same symbol,
                       // we've found a unifying counterexample.
-                      cex = new_counterexample (d1, d2, true, false);
+                      cex = new_counterexample (d1, d2, shift_reduce, true, false);
                       derivation_retain (d1);
                       derivation_retain (d2);
                       goto cex_search_end;
@@ -1142,7 +1194,7 @@ cex_search_end:;
       // If a search state from Stage 3 is available, use it
       // to construct a more compact nonunifying counterexample.
       if (stage3result)
-        cex = complete_diverging_examples (stage3result, next_sym);
+        cex = complete_diverging_examples (stage3result, next_sym, shift_reduce);
       // Otherwise, construct a nonunifying counterexample that
       // begins from the start state using the shortest
       // lookahead-sensitive path to the reduce item.
@@ -1190,7 +1242,7 @@ counterexample_report (state_item_number itm1, state_item_number itm2,
 {
   // Compute the shortest lookahead-sensitive path and associated sets of
   // parser states.
-  gl_list_t shortest_path = shortest_path_from_start (itm1, next_sym);
+  state_item_list shortest_path = shortest_path_from_start (itm1, next_sym);
   bool reduce_prod_reached = false;
   const rule *reduce_rule = item_rule (state_items[itm1].item);
 
@@ -1219,14 +1271,24 @@ counterexample_report (state_item_number itm1, state_item_number itm2,
   free_counterexample (cex);
 }
 
+
+// ITM1 denotes a shift, ITM2 a reduce.
 static void
 counterexample_report_shift_reduce (state_item_number itm1, state_item_number itm2,
                                     symbol_number next_sym,
                                     FILE *out, const char *prefix)
 {
-  fputs (prefix, out);
+  if (out == stderr)
-  fprintf (out, _("Shift/reduce conflict on token %s:\n"), symbols[next_sym]->tag);
+    complain (NULL, Wcounterexamples,
-  if (*prefix)
+              _("shift/reduce conflict on token %s"), symbols[next_sym]->tag);
+  else
+    {
+      fputs (prefix, out);
+      fprintf (out, _("shift/reduce conflict on token %s"), symbols[next_sym]->tag);
+      fprintf (out, "%s\n", _(":"));
+    }
+  // In the report, print the items.
+  if (out != stderr || trace_flag & trace_cex)
     {
       print_state_item (&state_items[itm1], out, prefix);
       print_state_item (&state_items[itm2], out, prefix);
@@ -1240,32 +1302,49 @@ counterexample_report_reduce_reduce (state_item_number itm1, state_item_number i
                                      FILE *out, const char *prefix)
 {
   {
-    fputs (prefix, out);
+    struct obstack obstack;
-    fputs (ngettext ("Reduce/reduce conflict on token",
+    obstack_init (&obstack);
-                     "Reduce/reduce conflict on tokens",
-                     bitset_count (conflict_syms)), out);
     bitset_iterator biter;
     state_item_number sym;
-    const char *sep = " ";
+    const char *sep = "";
     BITSET_FOR_EACH (biter, conflict_syms, sym, 0)
       {
-        fprintf (out, "%s%s", sep, symbols[sym]->tag);
+        obstack_printf (&obstack, "%s%s", sep, symbols[sym]->tag);
         sep = ", ";
       }
-    fputs (_(":\n"), out);
+    char *tokens = obstack_finish0 (&obstack);
+    if (out == stderr)
+      complain (NULL, Wcounterexamples,
+                ngettext ("reduce/reduce conflict on token %s",
+                          "reduce/reduce conflict on tokens %s",
+                          bitset_count (conflict_syms)),
+                tokens);
+    else
+      {
+        fputs (prefix, out);
+        fprintf (out,
+                 ngettext ("reduce/reduce conflict on token %s",
+                           "reduce/reduce conflict on tokens %s",
+                           bitset_count (conflict_syms)),
+                 tokens);
+        fprintf (out, "%s\n", _(":"));
+      }
+    obstack_free (&obstack, NULL);
   }
-  if (*prefix)
+  // In the report, print the items.
+  if (out != stderr || trace_flag & trace_cex)
     {
       print_state_item (&state_items[itm1], out, prefix);
       print_state_item (&state_items[itm2], out, prefix);
     }
-  counterexample_report (itm1, itm2, bitset_first (conflict_syms), false, out, prefix);
+  counterexample_report (itm1, itm2, bitset_first (conflict_syms),
+                         false, out, prefix);
 }
 
 static state_item_number
 find_state_item_number (const rule *r, state_number sn)
 {
-  for (int i = state_item_map[sn]; i < state_item_map[sn + 1]; ++i)
+  for (state_item_number i = state_item_map[sn]; i < state_item_map[sn + 1]; ++i)
     if (!SI_DISABLED (i)
         && item_number_as_rule_number (*state_items[i].item) == r->number)
       return i;
@@ -1277,41 +1356,35 @@ counterexample_report_state (const state *s, FILE *out, const char *prefix)
 {
   const state_number sn = s->number;
   const reductions *reds = s->reductions;
+  bitset lookaheads = bitset_create (ntokens, BITSET_FIXED);
   for (int i = 0; i < reds->num; ++i)
     {
       const rule *r1 = reds->rules[i];
       const state_item_number c1 = find_state_item_number (r1, sn);
-      for (int j = state_item_map[sn]; j < state_item_map[sn + 1]; ++j)
+      for (state_item_number c2 = state_item_map[sn]; c2 < state_item_map[sn + 1]; ++c2)
-        if (!SI_DISABLED (j))
+        if (!SI_DISABLED (c2))
           {
-            state_item *si = state_items + j;
+            item_number conf = *state_items[c2].item;
-            item_number conf = *si->item;
             if (item_number_is_symbol_number (conf)
-              && bitset_test (reds->lookahead_tokens[i], conf))
+                && bitset_test (reds->lookaheads[i], conf))
-              counterexample_report_shift_reduce (c1, j, conf, out, prefix);
+              counterexample_report_shift_reduce (c1, c2, conf, out, prefix);
           }
       for (int j = i+1; j < reds->num; ++j)
         {
-          bitset conf = bitset_create (ntokens, BITSET_FIXED);
+          const rule *r2 = reds->rules[j];
-          bitset_intersection (conf,
+          // Conflicts: common lookaheads.
-                               reds->lookahead_tokens[i],
+          bitset_intersection (lookaheads,
-                               reds->lookahead_tokens[j]);
+                               reds->lookaheads[i],
-          if (!bitset_empty_p (conf))
+                               reds->lookaheads[j]);
-            {
+          if (!bitset_empty_p (lookaheads))
-              const rule *r2 = reds->rules[j];
+            for (state_item_number c2 = state_item_map[sn]; c2 < state_item_map[sn + 1]; ++c2)
-              for (int k = state_item_map[sn]; k < state_item_map[sn + 1]; ++k)
+              if (!SI_DISABLED (c2)
-                if (!SI_DISABLED (k))
+                  && item_rule (state_items[c2].item) == r2)
-                  {
+                {
-                    state_item *si = state_items + k;
+                  counterexample_report_reduce_reduce (c1, c2, lookaheads, out, prefix);
-                    const rule *r = item_rule (si->item);
+                  break;
-                    if (r == r2)
+                }
-                      {
-                        counterexample_report_reduce_reduce (c1, k, conf, out, prefix);
-                        break;
-                      }
-                  }
-            }
-          bitset_free (conf);
         }
     }
+  bitset_free (lookaheads);
 }

src/counterexample.h

@@ -20,11 +20,17 @@
 #ifndef COUNTEREXAMPLE_H
 # define COUNTEREXAMPLE_H
 
-# include "state-item.h"
+# include "state.h"
 
+// Init/deinit this module.
 void counterexample_init (void);
 void counterexample_free (void);
 
-void counterexample_report_state (const state *s, FILE *out, const char *prefix);
+// Print the counterexamples for the conflicts of state S.
+//
+// Used both for the warnings on the terminal (OUT = stderr, PREFIX =
+// ""), and for the reports (OUT != stderr, PREFIX != "").
+void
+counterexample_report_state (const state *s, FILE *out, const char *prefix);
 
 #endif /* COUNTEREXAMPLE_H */

src/derivation.c

@@ -20,8 +20,11 @@
 #include <config.h>
 
 #include "derivation.h"
+#include "glyphs.h"
 
+#include <c-ctype.h>
 #include <gl_linked_list.h>
+#include <mbswidth.h>
 
 #include "system.h"
 #include "complain.h"
@@ -29,11 +32,15 @@
 struct derivation
 {
   symbol_number sym;
-  gl_list_t children;
+  derivation_list children;
   int reference_count;
+  // Color assigned for styling.  Guarantees that the derivation is
+  // always displayed with the same color, independently of the order
+  // in which the derivations are traversed.
+  int color;
 };
 
-static derivation d_dot = { -1, NULL, -1 };
+static derivation d_dot = { -1, NULL, -1, -1 };
 
 derivation *
 derivation_dot (void)
@@ -73,6 +80,7 @@ derivation_new (symbol_number sym, derivation_list children)
   deriv->sym = sym;
   deriv->children = children;
   deriv->reference_count = 0;
+  deriv->color = -1;
   return deriv;
 }
 
@@ -126,27 +134,242 @@ derivation_size (const derivation *deriv)
   return size;
 }
 
-/* Print DERIV, colored according to COUNTER.
+
-   Return false if nothing is printed.  */
+static int
+max (int a, int b)
+{
+  return a < b ? b : a;
+}
+
+// Longest distance from root to leaf.
+static int
+derivation_depth (const derivation *deriv)
+{
+  if (deriv->children)
+    {
+      // Children's depth cannot be 0, even if there are no children
+      // (the case of a derivation with an empty RHS).
+      int res = 1;
+      derivation *child;
+      for (gl_list_iterator_t it = gl_list_iterator (deriv->children);
+           derivation_list_next (&it, &child);
+           )
+        res = max (res, derivation_depth (child));
+      return res + 1;
+    }
+  else
+    return 1;
+}
+
 static bool
-derivation_print_impl (const derivation *deriv, FILE *f,
+all_spaces (const char *s)
-                       bool leaves_only,
+{
-                       int *counter, const char *prefix)
+  while (c_isspace (*s))
+    s++;
+  return *s == '\0';
+}
+
+// Printing the derivation as trees without trailing spaces is
+// painful: we cannot simply pad one "column" before moving to the
+// next:
+//
+// exp
+// ↳ x1          e1  foo1                      x1
+//   ↳ x2        ↳ ε ↳ foo2                    ↳ x2
+//     ↳ x3            ↳ foo3                    ↳ x3
+//       ↳ "X" •         ↳ x1        foo4          ↳ "X"
+//                         ↳ x2      ↳ "quuux"
+//                           ↳ x3
+//                             ↳ "X"
+//
+// It's hard for a column to know that it's "last" to decide whether
+// to output the right-padding or not.  So when we need to pad on the
+// right to complete a column, we don't output the spaces, we
+// accumulate the width of padding in *PADDING.
+//
+// Each time we actually print something (non space), we flush that
+// padding.  When we _don't_ print something, its width is added to
+// the current padding.
+//
+// This function implements this.
+//
+// When COND is true, put S on OUT, preceded by *PADDING white spaces.
+// Otherwise add the width to *PADDING.  Return the width of S.
+static int
+fputs_if (bool cond, FILE *out, int *padding, const char *s)
+{
+  int res = mbswidth (s, 0);
+  if (cond && !all_spaces (s))
+    {
+      fprintf (out, "%*s%s", *padding, "", s);
+      *padding = 0;
+    }
+  else
+    {
+      *padding += res;
+    }
+  return res;
+}
+
+// The width taken to report this derivation recursively down to its
+// leaves.
+static int
+derivation_width (const derivation *deriv)
 {
+  if (deriv->children)
+    {
+      const symbol *sym = symbols[deriv->sym];
+      int self_width = mbswidth (sym->tag, 0);
+
+      // Arrow and space.
+      int children_width = down_arrow_width;
+      if (gl_list_size (deriv->children) == 0)
+        // Empty rhs.
+        children_width += empty_width;
+      else
+        {
+          derivation *child;
+          for (gl_list_iterator_t it = gl_list_iterator (deriv->children);
+               derivation_list_next (&it, &child);
+               )
+            children_width
+              += derivation_separator_width + derivation_width (child);
+          // No separator at the beginning.
+          children_width -= derivation_separator_width;
+        }
+      return max (self_width, children_width);
+    }
+  else if (deriv == &d_dot)
+    {
+      return dot_width;
+    }
+  else // leaf.
+    {
+      const symbol *sym = symbols[deriv->sym];
+      return mbswidth (sym->tag, 0);
+    }
+}
+
+
+// Print DERIV for DEPTH.
+//
+// The tree is printed from top to bottom with DEPTH ranging from 0 to
+// the total depth of the tree.  DERIV should only printed when we
+// reach its depth, i.e., then DEPTH is 0.
+//
+// When DEPTH is 1 and we're on a subderivation, then we print the RHS
+// of the derivation (in DEPTH 0 we printed its LHS).
+//
+// Return the "logical printed" width.  We might have not have reached
+// that width, in which case the missing spaces are in *PADDING.
+static int
+derivation_print_tree_impl (const derivation *deriv, FILE *out,
+                            int depth, int *padding)
+{
+  const int width = derivation_width (deriv);
+
+  int res = 0;
   if (deriv->children)
     {
       const symbol *sym = symbols[deriv->sym];
       char style[20];
-      snprintf (style, 20, "cex-%d", *counter);
+      snprintf (style, 20, "cex-%d", deriv->color);
+
+      if (depth == 0 || depth == 1)
+        {
+          begin_use_class (style, out);
+          begin_use_class ("cex-step", out);
+        }
+      if (depth == 0)
+        {
+          res += fputs_if (true, out, padding, sym->tag);
+        }
+      else
+        {
+          res += fputs_if (depth == 1, out, padding, down_arrow);
+          if (gl_list_size (deriv->children) == 0)
+            // Empty rhs.
+            res += fputs_if (depth == 1, out, padding, empty);
+          else
+            {
+              bool first = true;
+              derivation *child;
+              for (gl_list_iterator_t it = gl_list_iterator (deriv->children);
+                   derivation_list_next (&it, &child);
+                   )
+                {
+                  if (!first)
+                    res += fputs_if (depth == 1, out, padding, derivation_separator);
+                  res += derivation_print_tree_impl (child, out, depth - 1, padding);
+                  first = false;
+                }
+            }
+        }
+      if (depth == 0 || depth == 1)
+        {
+          end_use_class ("cex-step", out);
+          end_use_class (style, out);
+        }
+      *padding += width - res;
+      res = width;
+    }
+  else if (deriv == &d_dot)
+    {
+      if (depth == 0)
+        begin_use_class ("cex-dot", out);
+      res += fputs_if (depth == 0, out, padding, dot);
+      if (depth == 0)
+        end_use_class ("cex-dot", out);
+    }
+  else // leaf.
+    {
+      const symbol *sym = symbols[deriv->sym];
+      if (depth == 0)
+        begin_use_class ("cex-leaf", out);
+      res += fputs_if (depth == 0, out, padding, sym->tag);
+      if (depth == 0)
+        end_use_class ("cex-leaf", out);
+    }
+  return res;
+}
+
+static void
+derivation_print_tree (const derivation *deriv, FILE *out, const char *prefix)
+{
+  fputc ('\n', out);
+  for (int depth = 0, max_depth = derivation_depth (deriv);
+       depth < max_depth; ++depth)
+    {
+      int padding = 0;
+      fprintf (out, "    %s", prefix);
+      derivation_print_tree_impl (deriv, out, depth, &padding);
+      fputc ('\n', out);
+    }
+}
+
+
+/* Print DERIV, colored according to COUNTER.
+   Return false if nothing is printed.  */
+static bool
+derivation_print_flat_impl (derivation *deriv, FILE *out,
+                            bool leaves_only,
+                            int *counter, const char *prefix)
+{
+  if (deriv->children)
+    {
+      const symbol *sym = symbols[deriv->sym];
+      deriv->color = *counter;
       ++*counter;
-      begin_use_class (style, f);
+      char style[20];
+      snprintf (style, 20, "cex-%d", deriv->color);
+      begin_use_class (style, out);
 
       if (!leaves_only)
         {
-          fputs (prefix, f);
+          fputs (prefix, out);
-          begin_use_class ("cex-step", f);
+          begin_use_class ("cex-step", out);
-          fprintf (f, "%s ::=[ ", sym->tag);
+          fprintf (out, "%s %s [ ", sym->tag, arrow);
-          end_use_class ("cex-step", f);
+          end_use_class ("cex-step", out);
           prefix = "";
         }
       bool res = false;
@@ -155,7 +378,8 @@ derivation_print_impl (const derivation *deriv, FILE *f,
            derivation_list_next (&it, &child);
            )
         {
-          if (derivation_print_impl (child, f, leaves_only, counter, prefix))
+          if (derivation_print_flat_impl (child, out,
+                                          leaves_only, counter, prefix))
             {
               prefix = " ";
               res = true;
@@ -165,49 +389,56 @@ derivation_print_impl (const derivation *deriv, FILE *f,
         }
       if (!leaves_only)
         {
-          begin_use_class ("cex-step", f);
+          begin_use_class ("cex-step", out);
           if (res)
-            fputs (" ]", f);
+            fputs (" ]", out);
           else
-            fputs ("]", f);
+            fputs ("]", out);
-          end_use_class ("cex-step", f);
+          end_use_class ("cex-step", out);
         }
-      end_use_class (style, f);
+      end_use_class (style, out);
       return res;
     }
   else if (deriv == &d_dot)
     {
-      fputs (prefix, f);
+      fputs (prefix, out);
-      begin_use_class ("cex-dot", f);
+      begin_use_class ("cex-dot", out);
-      print_dot (f);
+      fputs (dot, out);
-      end_use_class ("cex-dot", f);
+      end_use_class ("cex-dot", out);
     }
   else // leaf.
     {
-      fputs (prefix, f);
+      fputs (prefix, out);
       const symbol *sym = symbols[deriv->sym];
-      begin_use_class ("cex-leaf", f);
+      begin_use_class ("cex-leaf", out);
-      fprintf (f, "%s", sym->tag);
+      fprintf (out, "%s", sym->tag);
-      end_use_class ("cex-leaf", f);
+      end_use_class ("cex-leaf", out);
     }
   return true;
 }
 
+static void
+derivation_print_flat (const derivation *deriv, FILE *out, const char *prefix)
+{
+  int counter = 0;
+  fputs (prefix, out);
+  derivation_print_flat_impl ((derivation *)deriv, out, false, &counter, "");
+  fputc ('\n', out);
+}
+
+void
+derivation_print_leaves (const derivation *deriv, FILE *out)
+{
+  int counter = 0;
+  derivation_print_flat_impl ((derivation *)deriv, out, true, &counter, "");
+  fputc ('\n', out);
+}
+
 void
 derivation_print (const derivation *deriv, FILE *out, const char *prefix)
 {
-  int counter = 0;
+  if (getenv ("YYFLAT"))
-  fputs (prefix, out);
+    derivation_print_flat (deriv, out, prefix);
-  derivation_print_impl (deriv, out, false, &counter, "");
+  else
-  fputc ('\n', out);
+    derivation_print_tree (deriv, out, prefix);
-}
-
-
-void
-derivation_print_leaves (const derivation *deriv, FILE *out, const char *prefix)
-{
-  int counter = 0;
-  fputs (prefix, out);
-  derivation_print_impl (deriv, out, true, &counter, "");
-  fputc ('\n', out);
 }

src/derivation.h

@@ -60,12 +60,15 @@ static inline derivation *derivation_new_leaf (symbol_number sym)
 {
   return derivation_new (sym, NULL);
 }
+
+// Number of symbols.
 size_t derivation_size (const derivation *deriv);
 void derivation_print (const derivation *deriv, FILE *out, const char *prefix);
-void derivation_print_leaves (const derivation *deriv, FILE *out, const char *prefix);
+void derivation_print_leaves (const derivation *deriv, FILE *out);
 void derivation_free (derivation *deriv);
 void derivation_retain (derivation *deriv);
 
+// A derivation denoting the position of the dot.
 derivation *derivation_dot (void);
 
 #endif /* DERIVATION_H */

src/getargs.c

@@ -221,7 +221,7 @@ static const argmatch_report_arg argmatch_report_args[] =
   { "none",            report_none },
   { "states",          report_states },
   { "itemsets",        report_states | report_itemsets },
-  { "lookaheads",      report_states | report_lookahead_tokens },
+  { "lookaheads",      report_states | report_lookaheads },
   { "solved",          report_states | report_solved_conflicts },
   { "counterexamples", report_cex },
   { "cex",             report_cex },

src/getargs.h

@@ -77,7 +77,7 @@ enum report
     report_none             = 0,
     report_states           = 1 << 0,
     report_itemsets         = 1 << 1,
-    report_lookahead_tokens = 1 << 2,
+    report_lookaheads       = 1 << 2,
     report_solved_conflicts = 1 << 3,
     report_cex              = 1 << 4,
     report_all              = ~0

src/glyphs.c

@@ -0,0 +1,93 @@
+/* Graphical symbols.
+
+   Copyright (C) 2020 Free Software Foundation, Inc.
+
+   This file is part of Bison, the GNU Compiler Compiler.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#include "glyphs.h"
+
+#include <assert.h>
+#include <attribute.h>
+#include <stdbool.h>
+#include <string.h>
+#include <mbswidth.h>
+#include <unicodeio.h>
+
+
+glyph_buffer_t arrow;
+int arrow_width;
+
+glyph_buffer_t down_arrow;
+int down_arrow_width;
+
+glyph_buffer_t dot;
+int dot_width;
+
+glyph_buffer_t empty;
+int empty_width;
+
+const char *derivation_separator = " ";
+int derivation_separator_width = 1;
+
+typedef struct
+{
+  glyph_buffer_t *pbuf;
+  const char *fallback;
+} callback_arg_t;
+
+
+static long
+on_success (const char *buf, size_t buflen, void *callback_arg)
+{
+  callback_arg_t *arg = (callback_arg_t *) callback_arg;
+  assert (buflen + 1 < sizeof *arg->pbuf);
+  *stpncpy (*arg->pbuf, buf, buflen) = '\0';
+  return 1;
+}
+
+static long
+on_failure (unsigned code MAYBE_UNUSED, const char *msg MAYBE_UNUSED,
+            void *callback_arg)
+{
+  callback_arg_t *arg = (callback_arg_t *) callback_arg;
+  assert (strlen (arg->fallback) + 1 < sizeof *arg->pbuf);
+  strcpy (*arg->pbuf, arg->fallback);
+  return 0;
+}
+
+static bool
+glyph_set (glyph_buffer_t *glyph, int *width,
+           unsigned code, const char *fallback)
+{
+  callback_arg_t arg = { glyph, fallback };
+  int res = unicode_to_mb (code, on_success, on_failure, &arg);
+  *width = mbswidth (*glyph, 0);
+  return res;
+}
+
+void
+glyphs_init (void)
+{
+  glyph_set (&arrow,      &arrow_width,      0x2192, "->");
+  glyph_set (&dot,        &dot_width,        0x2022, ".");
+  glyph_set (&down_arrow, &down_arrow_width, 0x21b3, "`->");
+  glyph_set (&empty,      &empty_width,      0x03b5, "%empty");
+
+  strncat (down_arrow, " ", sizeof down_arrow - strlen (down_arrow) - 1);
+  down_arrow_width += 1;
+}

src/glyphs.h

@@ -0,0 +1,50 @@
+/* Graphical symbols.
+
+   Copyright (C) 2020 Free Software Foundation, Inc.
+
+   This file is part of Bison, the GNU Compiler Compiler.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef GLYPHS_H
+# define GLYPHS_H
+
+/* Initialize the following variables.  */
+void glyphs_init (void);
+
+/* In gnulib/lib/unicodeio.h unicode_to_mb uses a buffer of 25 bytes.
+   In down_arrow, we append one space.  */
+typedef char glyph_buffer_t[26];
+
+/* "→", separates the lhs of a rule from its rhs.  */
+extern glyph_buffer_t arrow;
+extern int arrow_width;
+
+/* "•", a point in an item (aka, a dotted rule).  */
+extern glyph_buffer_t dot;
+extern int dot_width;
+
+/* "↳ ", below an lhs to announce the rhs.  */
+extern glyph_buffer_t down_arrow;
+extern int down_arrow_width;
+
+/* "ε", an empty rhs.  */
+extern glyph_buffer_t empty;
+extern int empty_width;
+
+/* " ", separate symbols in the rhs of a derivation.  */
+extern const char *derivation_separator;
+extern int derivation_separator_width;
+
+#endif /* GLYPHS_H */

src/gram.c

@@ -23,6 +23,7 @@
 
 #include "complain.h"
 #include "getargs.h"
+#include "glyphs.h"
 #include "gram.h"
 #include "print-xml.h"
 #include "reader.h"
@@ -56,8 +57,7 @@ item_print (item_number *item, rule const *previous_rule, FILE *out)
 
   for (item_number *sp = r->rhs; sp < item; sp++)
     fprintf (out, " %s", symbols[*sp]->tag);
-  putc (' ', out);
+  fprintf (out, " %s", dot);
-  print_dot (out);
   if (0 <= *r->rhs)
     for (item_number *sp = item; 0 <= *sp; ++sp)
       fprintf (out, " %s", symbols[*sp]->tag);

src/gram.h

@@ -103,8 +103,6 @@
 
 # include "system.h"
 
-# include <unicodeio.h>
-
 # include "location.h"
 # include "symtab.h"
 
@@ -217,25 +215,6 @@ typedef struct
 extern rule *rules;
 extern rule_number nrules;
 
-/* Fallback in case we can't print "•".  */
-static inline long
-print_dot_fallback (unsigned int code _GL_UNUSED,
-                    const char *msg _GL_UNUSED,
-                    void *callback_arg)
-{
-  FILE *out = (FILE *) callback_arg;
-  putc ('.', out);
-  return -1;
-}
-
-/* Print "•", the symbol used to represent a point in an item (aka, a
-   dotted rule).  */
-static inline void
-print_dot (FILE *out)
-{
-  unicode_to_mb (0x2022, fwrite_success_callback, print_dot_fallback, out);
-}
-
 /* Get the rule associated to this item.  ITEM points inside RITEM.  */
 static inline rule const *
 item_rule (item_number const *item)

src/graphviz.c

@@ -184,9 +184,9 @@ output_red (state const *s, reductions const *reds, FILE *fout)
       bool firste = true;
       rule_number ruleno = reds->rules[j]->number;
 
-      if (reds->lookahead_tokens)
+      if (reds->lookaheads)
         for (int i = 0; i < ntokens; i++)
-          if (bitset_test (reds->lookahead_tokens[j], i))
+          if (bitset_test (reds->lookaheads[j], i))
             {
               if (bitset_test (no_reduce_set, i))
                 firstd = print_token (&dout, firstd, symbols[i]->tag);

src/ielr.c

@@ -1025,7 +1025,7 @@ ielr_split_states (bitsetv follow_kernel_items, bitsetv always_follows,
               {
                 rule *this_rule = node->state->reductions->rules[r];
                 bitset lookahead_set =
-                  node->state->reductions->lookahead_tokens[r];
+                  node->state->reductions->lookaheads[r];
                 if (item_number_is_rule_number (*this_rule->rhs))
                   ielr_compute_goto_follow_set (follow_kernel_items,
                                                 always_follows, node,

src/lalr.c

@@ -256,9 +256,9 @@ lookback_find_state (int lookback_index)
   state *res = NULL;
   for (int j = 0; j < nstates; ++j)
     if (states[j]->reductions
-        && states[j]->reductions->lookahead_tokens)
+        && states[j]->reductions->lookaheads)
       {
-        if (states[j]->reductions->lookahead_tokens - LA > lookback_index)
+        if (states[j]->reductions->lookaheads - LA > lookback_index)
           /* Went too far. */
           break;
         else
@@ -280,7 +280,7 @@ lookback_print (FILE *out)
     {
       fprintf (out, "   %3d = ", i);
       const state *s = lookback_find_state (i);
-      int rnum = i - (s->reductions->lookahead_tokens - LA);
+      int rnum = i - (s->reductions->lookaheads - LA);
       const rule *r = s->reductions->rules[rnum];
       fprintf (out, "(%3d, ", s->number);
       rule_print (r, NULL, out);
@@ -305,7 +305,7 @@ static void
 add_lookback_edge (state *s, rule const *r, goto_number gotono)
 {
   int ri = state_reduction_find (s, r);
-  int idx = (s->reductions->lookahead_tokens - LA) + ri;
+  int idx = (s->reductions->lookaheads - LA) + ri;
   lookback[idx] = goto_list_new (gotono, lookback[idx]);
 }
 
@@ -421,7 +421,7 @@ compute_follows (void)
 
 
 static void
-compute_lookahead_tokens (void)
+compute_lookaheads (void)
 {
   if (trace_flag & trace_automaton)
       lookback_print (stderr);
@@ -437,13 +437,12 @@ compute_lookahead_tokens (void)
 }
 
 
-/*----------------------------------------------------.
+/*------------------------------------------------------.
-| Count the number of lookahead tokens required for S |
+| Count the number of lookahead tokens required for S.  |
-| (N_LOOKAHEAD_TOKENS member).                        |
+`------------------------------------------------------*/
-`----------------------------------------------------*/
 
 static int
-state_lookahead_tokens_count (state *s, bool default_reduction_only_for_accept)
+state_lookaheads_count (state *s, bool default_reduction_only_for_accept)
 {
   const reductions *reds = s->reductions;
   const transitions *trans = s->transitions;
@@ -473,9 +472,9 @@ state_lookahead_tokens_count (state *s, bool default_reduction_only_for_accept)
 }
 
 
-/*----------------------------------------------------.
+/*----------------------------------------------.
-| Compute LA, NLA, and the lookahead_tokens members.  |
+| Compute LA, NLA, and the lookaheads members.  |
-`----------------------------------------------------*/
+`----------------------------------------------*/
 
 void
 initialize_LA (void)
@@ -491,25 +490,23 @@ initialize_LA (void)
   /* Compute the total number of reductions requiring a lookahead.  */
   nLA = 0;
   for (state_number i = 0; i < nstates; ++i)
-    nLA +=
+    nLA += state_lookaheads_count (states[i],
-      state_lookahead_tokens_count (states[i],
+                                   default_reduction_only_for_accept);
-                                    default_reduction_only_for_accept);
   /* Avoid having to special case 0.  */
   if (!nLA)
     nLA = 1;
 
   bitsetv pLA = LA = bitsetv_create (nLA, ntokens, BITSET_FIXED);
 
-  /* Initialize the members LOOKAHEAD_TOKENS for each state whose reductions
+  /* Initialize the members LOOKAHEADS for each state whose reductions
      require lookahead tokens.  */
   for (state_number i = 0; i < nstates; ++i)
     {
-      int count =
+      int count = state_lookaheads_count (states[i],
-        state_lookahead_tokens_count (states[i],
+                                          default_reduction_only_for_accept);
-                                      default_reduction_only_for_accept);
       if (count)
         {
-          states[i]->reductions->lookahead_tokens = pLA;
+          states[i]->reductions->lookaheads = pLA;
           pLA += count;
         }
     }
@@ -521,7 +518,7 @@ initialize_LA (void)
 `---------------------------------------------*/
 
 static void
-lookahead_tokens_print (FILE *out)
+lookaheads_print (FILE *out)
 {
   fputs ("Lookaheads:\n", out);
   for (state_number i = 0; i < nstates; ++i)
@@ -533,11 +530,11 @@ lookahead_tokens_print (FILE *out)
           for (int j = 0; j < reds->num; ++j)
             {
               fprintf (out, "    rule %d:", reds->rules[j]->number);
-              if (reds->lookahead_tokens)
+              if (reds->lookaheads)
               {
                 bitset_iterator iter;
                 int k;
-                BITSET_FOR_EACH (iter, reds->lookahead_tokens[j], k, 0)
+                BITSET_FOR_EACH (iter, reds->lookaheads[j], k, 0)
                   fprintf (out, " %s", symbols[k]->tag);
               }
               fputc ('\n', out);
@@ -564,10 +561,10 @@ lalr (void)
   lookback = xcalloc (nLA, sizeof *lookback);
   build_relations ();
   compute_follows ();
-  compute_lookahead_tokens ();
+  compute_lookaheads ();
 
   if (trace_flag & trace_sets)
-    lookahead_tokens_print (stderr);
+    lookaheads_print (stderr);
   if (trace_flag & trace_automaton)
     {
       begin_use_class ("trace0", stderr);
@@ -614,6 +611,6 @@ void
 lalr_free (void)
 {
   for (state_number s = 0; s < nstates; ++s)
-    states[s]->reductions->lookahead_tokens = NULL;
+    states[s]->reductions->lookaheads = NULL;
   bitsetv_free (LA);
 }

src/local.mk

@@ -53,6 +53,8 @@ src_bison_SOURCES =                             \
   src/flex-scanner.h                            \
   src/getargs.c                                 \
   src/getargs.h                                 \
+  src/glyphs.c                                  \
+  src/glyphs.h                                  \
   src/gram.c                                    \
   src/gram.h                                    \
   src/graphviz.c                                \

src/lssi.c

@@ -82,8 +82,10 @@ lssi_comparator (lssi *s1, lssi *s2)
   return false;
 }
 
+typedef gl_list_t lssi_list;
+
 static inline bool
-append_lssi (lssi *sn, Hash_table *visited, gl_list_t queue)
+append_lssi (lssi *sn, Hash_table *visited, lssi_list queue)
 {
   if (hash_lookup (visited, sn))
     {
@@ -100,7 +102,7 @@ append_lssi (lssi *sn, Hash_table *visited, gl_list_t queue)
 static void
 lssi_print (lssi *l)
 {
-  print_state_item (state_items + l->si, stdout);
+  print_state_item (&state_items[l->si], stdout);
   if (l->lookahead)
     {
       printf ("FOLLOWL = { ");
@@ -121,7 +123,7 @@ static bitset
 eligible_state_items (state_item *target)
 {
   bitset result = bitset_create (nstate_items, BITSET_FIXED);
-  gl_list_t queue =
+  state_item_list queue =
     gl_list_create (GL_LINKED_LIST, NULL, NULL, NULL, true, 1,
                     (const void **) &target);
   while (gl_list_size (queue) > 0)
@@ -147,7 +149,7 @@ eligible_state_items (state_item *target)
  * this conflict. If optimized is true, only consider parser states
  * that can reach the conflict state.
  */
-gl_list_t
+state_item_list
 shortest_path_from_start (state_item_number target, symbol_number next_sym)
 {
   bitset eligible = eligible_state_items (&state_items[target]);
@@ -159,7 +161,7 @@ shortest_path_from_start (state_item_number target, symbol_number next_sym)
   bitset il = bitset_create (nsyms, BITSET_FIXED);
   bitset_set (il, 0);
   lssi *init = new_lssi (0, NULL, il, true);
-  gl_list_t queue = gl_list_create_empty (GL_LINKED_LIST, NULL, NULL,
+  lssi_list queue = gl_list_create_empty (GL_LINKED_LIST, NULL, NULL,
                                           NULL, true);
   append_lssi (init, visited, queue);
   // breadth-first search
@@ -175,7 +177,7 @@ shortest_path_from_start (state_item_number target, symbol_number next_sym)
           finished = true;
           break;
         }
-      state_item *si = state_items + last;
+      state_item *si = &state_items[last];
       // Transitions don't change follow_L
       if (si->trans >= 0)
         {
@@ -240,10 +242,10 @@ shortest_path_from_start (state_item_number target, symbol_number next_sym)
       fputs ("Cannot find shortest path to conflict state.", stderr);
       abort ();
     }
-  gl_list_t res =
+  state_item_list res =
     gl_list_create_empty (GL_LINKED_LIST, NULL, NULL, NULL, true);
   for (lssi *sn = n; sn != NULL; sn = sn->parent)
-    gl_list_add_first (res, state_items + sn->si);
+    gl_list_add_first (res, &state_items[sn->si]);
 
   hash_free (visited);
   gl_list_free (queue);
@@ -306,10 +308,10 @@ intersect (bitset ts, bitset syms)
  * Compute a list of state_items that have a production to n with respect
  * to its lookahead
  */
-gl_list_t
+state_item_list
 lssi_reverse_production (const state_item *si, bitset lookahead)
 {
-  gl_list_t result =
+  state_item_list result =
     gl_list_create_empty (GL_LINKED_LIST, NULL, NULL, NULL, true);
   if (SI_TRANSITION (si))
     return result;
@@ -320,7 +322,7 @@ lssi_reverse_production (const state_item *si, bitset lookahead)
   state_item_number sin;
   BITSET_FOR_EACH (biter, si->revs, sin, 0)
   {
-    state_item *prevsi = state_items + sin;
+    state_item *prevsi = &state_items[sin];
     if (!production_allowed (prevsi, si))
       continue;
     bitset prev_lookahead = prevsi->lookahead;

src/lssi.h

@@ -32,8 +32,8 @@
  * find shortest lookahead-sensitive path of state-items to target such that
  * next_sym is in the follow_L set of target in that position.
 */
-gl_list_t shortest_path_from_start (state_item_number target,
+state_item_list shortest_path_from_start (state_item_number target,
-                                    symbol_number next_sym);
+                                          symbol_number next_sym);
 
 /**
  * Determine if the given terminal is in the given symbol set or can begin
@@ -52,6 +52,6 @@ bool intersect (bitset ts, bitset syms);
  * to this state-item such that the resulting possible lookahead symbols are
  * as given.
  */
-gl_list_t lssi_reverse_production (const state_item *si, bitset lookahead);
+state_item_list lssi_reverse_production (const state_item *si, bitset lookahead);
 
 #endif /* LSSI_H */

src/main.c

@@ -38,6 +38,7 @@
 #include "files.h"
 #include "fixits.h"
 #include "getargs.h"
+#include "glyphs.h"
 #include "gram.h"
 #include "ielr.h"
 #include "lalr.h"
@@ -85,6 +86,7 @@ main (int argc, char *argv[])
 
   atexit (close_stdout);
 
+  glyphs_init ();
   uniqstrs_new ();
   muscle_init ();
   complain_init ();

src/parse-simulation.c

@@ -34,7 +34,7 @@ typedef struct parse_state
   struct si_chunk
   {
     // elements newly added in this chunk
-    gl_list_t contents;
+    state_item_list contents;
     // properties of the linked list this chunk represents
     const state_item *head_elt;
     const state_item *tail_elt;
@@ -135,7 +135,7 @@ static parse_state *
 copy_parse_state (bool prepend, parse_state *parent)
 {
   parse_state *res = xmalloc (sizeof *res);
-  memcpy (res, parent, sizeof *res);
+  *res = *parent;
   res->state_items.contents
     = gl_list_create_empty (GL_LINKED_LIST, NULL, NULL, NULL, true);
   res->derivs.contents = derivation_list_new ();
@@ -252,7 +252,7 @@ parse_state_completed_steps (const parse_state *ps, int *shifts, int *production
   while (root_ps->parent)
     root_ps = root_ps->parent;
 
-  gl_list_t sis = root_ps->state_items.contents;
+  state_item_list sis = root_ps->state_items.contents;
   int count = 0;
 
   state_item *last = NULL;
@@ -337,19 +337,17 @@ parser_pop (parse_state *ps, int deriv_index,
   for (int i = 0; i < 4; ++i)
     chunks[i] = gl_list_create_empty (GL_LINKED_LIST, NULL, NULL, NULL, true);
   for (parse_state *pn = ps; pn != NULL; pn = pn->parent)
-    {
+    if (pn->prepend)
-      if (pn->prepend)
+      {
-        {
+        gl_list_add_last (chunks[0], pn->state_items.contents);
-          gl_list_add_last (chunks[0], pn->state_items.contents);
+        gl_list_add_last (chunks[2], pn->derivs.contents);
-          gl_list_add_last (chunks[2], pn->derivs.contents);
+      }
-        }
+    else
-      else
+      {
-        {
+        gl_list_add_first (chunks[1], pn->state_items.contents);
-          gl_list_add_first (chunks[1], pn->state_items.contents);
+        gl_list_add_first (chunks[3], pn->derivs.contents);
-          gl_list_add_first (chunks[3], pn->derivs.contents);
+      }
-        }
+  derivation_list popped_derivs = derivation_list_new ();
-    }
-  gl_list_t popped_derivs = derivation_list_new ();
   gl_list_t ret_chunks[4] = { ret->state_items.contents, NULL,
     ret->derivs.contents, popped_derivs
   };
@@ -390,7 +388,7 @@ parser_pop (parse_state *ps, int deriv_index,
 }
 
 void
-parse_state_lists (parse_state *ps, gl_list_t *sitems,
+parse_state_lists (parse_state *ps, state_item_list *sitems,
                    derivation_list *derivs)
 {
   parse_state *temp = empty_parse_state ();
@@ -418,12 +416,12 @@ nullable_closure (parse_state *ps, state_item *si, parse_state_list state_list)
   for (state_item_number sin = si->trans; sin != -1;
        prev_sin = sin, sin = state_items[sin].trans)
     {
-      state_item *psi = state_items + prev_sin;
+      state_item *psi = &state_items[prev_sin];
       symbol_number sp = item_number_as_symbol_number (*psi->item);
       if (ISTOKEN (sp) || !nullable[sp - ntokens])
         break;
 
-      state_item *nsi = state_items + sin;
+      state_item *nsi = &state_items[sin];
       current_ps = copy_parse_state (false, current_ps);
       ps_si_append (current_ps, nsi);
       ps_derivs_append (current_ps, derivation_new (sp, derivation_list_new ()));
@@ -431,14 +429,14 @@ nullable_closure (parse_state *ps, state_item *si, parse_state_list state_list)
     }
 }
 
-gl_list_t
+parse_state_list
 simulate_transition (parse_state *ps)
 {
   const state_item *si = ps->state_items.tail_elt;
   symbol_number sym = item_number_as_symbol_number (*si->item);
   // Transition on the same next symbol, taking nullable
   // symbols into account.
-  gl_list_t result = parse_state_list_new ();
+  parse_state_list result = parse_state_list_new ();
   state_item_number si_next = si->trans;
   // check for disabled transition, shouldn't happen
   // as any state_items that lead to these should be
@@ -446,11 +444,11 @@ simulate_transition (parse_state *ps)
   if (si_next < 0)
     return result;
   parse_state *next_ps = copy_parse_state (false, ps);
-  ps_si_append (next_ps, state_items + si_next);
+  ps_si_append (next_ps, &state_items[si_next]);
   ps_derivs_append (next_ps, derivation_new_leaf (sym));
   parse_state_list_append (result, next_ps);
 
-  nullable_closure (next_ps, state_items + si_next, result);
+  nullable_closure (next_ps, &state_items[si_next], result);
   return result;
 }
 
@@ -473,10 +471,10 @@ compatible (symbol_number sym1, symbol_number sym2)
     return false;
 }
 
-gl_list_t
+parse_state_list
 simulate_production (parse_state *ps, symbol_number compat_sym)
 {
-  gl_list_t result = parse_state_list_new ();
+  parse_state_list result = parse_state_list_new ();
   const state_item *si = parse_state_tail (ps);
   if (si->prods)
     {
@@ -486,7 +484,7 @@ simulate_production (parse_state *ps, symbol_number compat_sym)
         {
           // Take production step only if lhs is not nullable and
           // if first rhs symbol is compatible with compat_sym
-          state_item *next = state_items + sin;
+          state_item *next = &state_items[sin];
           item_number *itm1 = next->item;
           if (!compatible (*itm1, compat_sym) || !production_allowed (si, next))
             continue;
@@ -504,10 +502,10 @@ simulate_production (parse_state *ps, symbol_number compat_sym)
 // simulates a reduction on the given parse state, conflict_item is the
 // item associated with ps's conflict. symbol_set is a lookahead set this
 // reduction must be compatible with
-gl_list_t
+parse_state_list
 simulate_reduction (parse_state *ps, int rule_len, bitset symbol_set)
 {
-  gl_list_t result = parse_state_list_new ();
+  parse_state_list result = parse_state_list_new ();
 
   int s_size = ps->state_items.total_size;
   int d_size = ps->derivs.total_size;
@@ -529,7 +527,7 @@ simulate_reduction (parse_state *ps, int rule_len, bitset symbol_set)
   if (s_size != rule_len + 1)
     {
       state_item *tail = (state_item *) new_root->state_items.tail_elt;
-      ps_si_append (new_root, state_items + tail->trans);
+      ps_si_append (new_root, &state_items[tail->trans]);
       parse_state_list_append (result, new_root);
     }
   else
@@ -537,7 +535,7 @@ simulate_reduction (parse_state *ps, int rule_len, bitset symbol_set)
       // The head state_item is a production item, so we need to prepend
       // with possible source state-items.
       const state_item *head = ps->state_items.head_elt;
-      gl_list_t prev = lssi_reverse_production (head, symbol_set);
+      state_item_list prev = lssi_reverse_production (head, symbol_set);
       // TODO: better understand what causes this case.
       if (gl_list_size (prev) == 0)
         {
@@ -560,7 +558,7 @@ simulate_reduction (parse_state *ps, int rule_len, bitset symbol_set)
               copy = copy_parse_state (false, copy);
               struct si_chunk *sis = &copy->state_items;
               const state_item *tail = sis->tail_elt;
-              ps_si_append (copy, state_items + tail->trans);
+              ps_si_append (copy, &state_items[tail->trans]);
               parse_state_list_append (result, copy);
               nullable_closure (copy, (state_item *) sis->tail_elt, result);
             }
@@ -570,10 +568,10 @@ simulate_reduction (parse_state *ps, int rule_len, bitset symbol_set)
   return result;
 }
 
-gl_list_t
+parse_state_list
 parser_prepend (parse_state *ps)
 {
-  gl_list_t res = parse_state_list_new ();
+  parse_state_list res = parse_state_list_new ();
   const state_item *head = ps->state_items.head_elt;
   symbol_number prepend_sym =
     item_number_as_symbol_number (*(head->item - 1));
@@ -582,7 +580,7 @@ parser_prepend (parse_state *ps)
   BITSET_FOR_EACH (biter, head->revs, sin, 0)
   {
     parse_state *copy = copy_parse_state (true, ps);
-    ps_si_prepend (copy, state_items + sin);
+    ps_si_prepend (copy, &state_items[sin]);
     if (SI_TRANSITION (head))
       ps_derivs_prepend (copy, derivation_new_leaf (prepend_sym));
     parse_state_list_append (res, copy);

src/parse-simulation.h

@@ -113,7 +113,7 @@ int parse_state_length (const parse_state *ps);
 int parse_state_depth (const parse_state *ps);
 
 /* returns the linked lists that the parse state is supposed to represent */
-void parse_state_lists (parse_state *ps, gl_list_t *state_items,
+void parse_state_lists (parse_state *ps, state_item_list *state_items,
                         derivation_list *derivs);
 
 /* various functions that return a list of states based off of

src/print-graph.c

@@ -96,7 +96,7 @@ print_core (struct obstack *oout, state *s)
         obstack_sgrow (oout, " %empty");
 
       /* Experimental feature: display the lookahead tokens. */
-      if (report_flag & report_lookahead_tokens
+      if (report_flag & report_lookaheads
           && item_number_is_rule_number (*sp1))
         {
           /* Find the reduction we are handling.  */
@@ -104,13 +104,13 @@ print_core (struct obstack *oout, state *s)
           int redno = state_reduction_find (s, r);
 
           /* Print them if there are.  */
-          if (reds->lookahead_tokens && redno != -1)
+          if (reds->lookaheads && redno != -1)
             {
               bitset_iterator biter;
               int k;
               char const *sep = "";
               obstack_sgrow (oout, "  [");
-              BITSET_FOR_EACH (biter, reds->lookahead_tokens[redno], k, 0)
+              BITSET_FOR_EACH (biter, reds->lookaheads[redno], k, 0)
                 {
                   obstack_sgrow (oout, sep);
                   obstack_backslash (oout, symbols[k]->tag);

src/print-xml.c

@@ -86,12 +86,12 @@ print_core (FILE *out, int level, state *s)
           reductions *reds = s->reductions;
           int red = state_reduction_find (s, r);
           /* Print item with lookaheads if there are. */
-          if (reds->lookahead_tokens && red != -1)
+          if (reds->lookaheads && red != -1)
             {
               xml_printf (out, level + 1,
                           "<item rule-number=\"%d\" dot=\"%d\">",
                           r->number, sp1 - sp);
-              state_rule_lookahead_tokens_print_xml (s, r,
+              state_rule_lookaheads_print_xml (s, r,
                                                      out, level + 2);
               xml_puts (out, level + 1, "</item>");
               printed = true;
@@ -202,26 +202,26 @@ print_errs (FILE *out, int level, state *s)
 }
 
 
-/*-------------------------------------------------------------------------.
+/*-------------------------------------------------------------------.
-| Report a reduction of RULE on LOOKAHEAD_TOKEN (which can be 'default').  |
+| Report a reduction of RULE on LOOKAHEAD (which can be 'default').  |
-| If not ENABLED, the rule is masked by a shift or a reduce (S/R and       |
+| If not ENABLED, the rule is masked by a shift or a reduce (S/R and |
-| R/R conflicts).                                                          |
+| R/R conflicts).                                                    |
-`-------------------------------------------------------------------------*/
+`-------------------------------------------------------------------*/
 
 static void
-print_reduction (FILE *out, int level, char const *lookahead_token,
+print_reduction (FILE *out, int level, char const *lookahead,
                  rule *r, bool enabled)
 {
   if (r->number)
     xml_printf (out, level,
                 "<reduction symbol=\"%s\" rule=\"%d\" enabled=\"%s\"/>",
-                xml_escape (lookahead_token),
+                xml_escape (lookahead),
                 r->number,
                 enabled ? "true" : "false");
   else
     xml_printf (out, level,
                 "<reduction symbol=\"%s\" rule=\"accept\" enabled=\"%s\"/>",
-                xml_escape (lookahead_token),
+                xml_escape (lookahead),
                 enabled ? "true" : "false");
 }
 
@@ -258,13 +258,13 @@ print_reductions (FILE *out, int level, state *s)
   if (default_reduction)
     report = true;
 
-  if (reds->lookahead_tokens)
+  if (reds->lookaheads)
     for (i = 0; i < ntokens; i++)
       {
         bool count = bitset_test (no_reduce_set, i);
 
         for (j = 0; j < reds->num; ++j)
-          if (bitset_test (reds->lookahead_tokens[j], i))
+          if (bitset_test (reds->lookaheads[j], i))
             {
               if (! count)
                 {
@@ -289,14 +289,14 @@ print_reductions (FILE *out, int level, state *s)
   xml_puts (out, level, "<reductions>");
 
   /* Report lookahead tokens (or $default) and reductions.  */
-  if (reds->lookahead_tokens)
+  if (reds->lookaheads)
     for (i = 0; i < ntokens; i++)
       {
         bool defaulted = false;
         bool count = bitset_test (no_reduce_set, i);
 
         for (j = 0; j < reds->num; ++j)
-          if (bitset_test (reds->lookahead_tokens[j], i))
+          if (bitset_test (reds->lookaheads[j], i))
             {
               if (! count)
                 {
@@ -382,14 +382,17 @@ print_grammar (FILE *out, int level)
   for (int i = 0; i < max_code + 1; i++)
     if (token_translations[i] != undeftoken->content->number)
       {
-        char const *tag = symbols[token_translations[i]]->tag;
+        symbol const *sym = symbols[token_translations[i]];
-        int precedence = symbols[token_translations[i]]->content->prec;
+        char const *tag = sym->tag;
-        assoc associativity = symbols[token_translations[i]]->content->assoc;
+        char const *type = sym->content->type_name;
+        int precedence = sym->content->prec;
+        assoc associativity = sym->content->assoc;
         xml_indent (out, level + 2);
         fprintf (out,
                  "<terminal symbol-number=\"%d\" token-number=\"%d\""
-                 " name=\"%s\" usefulness=\"%s\"",
+                 " name=\"%s\" type=\"%s\" usefulness=\"%s\"",
-                 token_translations[i], i, xml_escape (tag),
+                 token_translations[i], i, xml_escape_n (0, tag),
+                 type ? xml_escape_n (1, type) : "",
                  reduce_token_unused_in_grammar (token_translations[i])
                    ? "unused-in-grammar" : "useful");
         if (precedence)
@@ -404,12 +407,16 @@ print_grammar (FILE *out, int level)
   xml_puts (out, level + 1, "<nonterminals>");
   for (symbol_number i = ntokens; i < nsyms + nuseless_nonterminals; i++)
     {
-      char const *tag = symbols[i]->tag;
+      symbol const *sym = symbols[i];
+      char const *tag = sym->tag;
+      char const *type = sym->content->type_name;
       xml_printf (out, level + 2,
                   "<nonterminal symbol-number=\"%d\" name=\"%s\""
+                  " type=\"%s\""
                   " usefulness=\"%s\"/>",
-                  i, xml_escape (tag),
+                  i, xml_escape_n (0, tag),
-                  reduce_nonterminal_useless_in_grammar (symbols[i]->content)
+                  type ? xml_escape_n (1, type) : "",
+                  reduce_nonterminal_useless_in_grammar (sym->content)
                     ? "useless-in-grammar" : "useful");
     }
   xml_puts (out, level + 1, "</nonterminals>");

src/print.c

@@ -90,9 +90,9 @@ print_core (FILE *out, const state *s)
       previous_rule = r;
 
       /* Display the lookahead tokens?  */
-      if (report_flag & report_lookahead_tokens
+      if (report_flag & report_lookaheads
           && item_number_is_rule_number (*sp1))
-        state_rule_lookahead_tokens_print (s, r, out);
+        state_rule_lookaheads_print (s, r, out);
       fputc ('\n', out);
     }
 }
@@ -180,19 +180,19 @@ print_errs (FILE *out, const state *s)
 }
 
 
-/*-------------------------------------------------------------------------.
+/*-------------------------------------------------------------------.
-| Report a reduction of RULE on LOOKAHEAD_TOKEN (which can be 'default').  |
+| Report a reduction of RULE on LOOKAHEAD (which can be 'default').  |
-| If not ENABLED, the rule is masked by a shift or a reduce (S/R and       |
+| If not ENABLED, the rule is masked by a shift or a reduce (S/R and |
-| R/R conflicts).                                                          |
+| R/R conflicts).                                                    |
-`-------------------------------------------------------------------------*/
+`-------------------------------------------------------------------*/
 
 static void
 print_reduction (FILE *out, size_t width,
-                 const char *lookahead_token,
+                 const char *lookahead,
                  rule *r, bool enabled)
 {
-  fprintf (out, "    %s", lookahead_token);
+  fprintf (out, "    %s", lookahead);
-  for (int j = width - mbswidth (lookahead_token, 0); j > 0; --j)
+  for (int j = width - mbswidth (lookahead, 0); j > 0; --j)
     fputc (' ', out);
   if (!enabled)
     fputc ('[', out);
@@ -239,13 +239,13 @@ print_reductions (FILE *out, const state *s)
   if (default_reduction)
     width = mbswidth (_("$default"), 0);
 
-  if (reds->lookahead_tokens)
+  if (reds->lookaheads)
     for (int i = 0; i < ntokens; i++)
       {
         bool count = bitset_test (no_reduce_set, i);
 
         for (int j = 0; j < reds->num; ++j)
-          if (bitset_test (reds->lookahead_tokens[j], i))
+          if (bitset_test (reds->lookaheads[j], i))
             {
               if (! count)
                 {
@@ -268,7 +268,7 @@ print_reductions (FILE *out, const state *s)
   bool default_reduction_only = true;
 
   /* Report lookahead tokens (or $default) and reductions.  */
-  if (reds->lookahead_tokens)
+  if (reds->lookaheads)
     for (int i = 0; i < ntokens; i++)
       {
         bool defaulted = false;
@@ -277,7 +277,7 @@ print_reductions (FILE *out, const state *s)
           default_reduction_only = false;
 
         for (int j = 0; j < reds->num; ++j)
-          if (bitset_test (reds->lookahead_tokens[j], i))
+          if (bitset_test (reds->lookaheads[j], i))
             {
               if (! count)
                 {
@@ -377,11 +377,11 @@ print_terminal_symbols (FILE *out)
   for (int i = 0; i < max_code + 1; ++i)
     if (token_translations[i] != undeftoken->content->number)
       {
-        const char *tag = symbols[token_translations[i]]->tag;
+        const symbol *sym = symbols[token_translations[i]];
+        const char *tag = sym->tag;
         fprintf (out, "%4s%s", "", tag);
-        if (symbols[token_translations[i]]->content->type_name)
+        if (sym->content->type_name)
-          fprintf (out, " <%s>",
+          fprintf (out, " <%s>", sym->content->type_name);
-                   symbols[token_translations[i]]->content->type_name);
         fprintf (out, " (%d)", i);
 
         for (rule_number r = 0; r < nrules; r++)
@@ -403,7 +403,8 @@ print_nonterminal_symbols (FILE *out)
   fprintf (out, "%s\n\n", _("Nonterminals, with rules where they appear"));
   for (symbol_number i = ntokens; i < nsyms; i++)
     {
-      const char *tag = symbols[i]->tag;
+      const symbol *sym = symbols[i];
+      const char *tag = sym->tag;
       bool on_left = false;
       bool on_right = false;
 
@@ -418,9 +419,9 @@ print_nonterminal_symbols (FILE *out)
 
       int column = 4 + mbswidth (tag, 0);
       fprintf (out, "%4s%s", "", tag);
-      if (symbols[i]->content->type_name)
+      if (sym->content->type_name)
         column += fprintf (out, " <%s>",
-                           symbols[i]->content->type_name);
+                           sym->content->type_name);
       fprintf (out, " (%d)\n", i);
 
       if (on_left)

src/state-item.c

@@ -144,13 +144,13 @@ init_state_items (void)
       for (int j = 0; j < s->nitems; ++j)
         {
           state_item_set (sidx, s, s->items[j]);
-          state_item *si = state_items + sidx;
+          state_item *si = &state_items[sidx];
           const rule *r = item_rule (si->item);
           if (rule_search_idx < red->num && red->rules[rule_search_idx] < r)
             ++rule_search_idx;
           if (rule_search_idx < red->num && r == red->rules[rule_search_idx])
             {
-              bitsetv lookahead = red->lookahead_tokens;
+              bitsetv lookahead = red->lookaheads;
               if (lookahead)
                 si->lookahead = lookahead[rule_search_idx];
             }
@@ -163,7 +163,7 @@ init_state_items (void)
           state_item_set (sidx, s, off);
           if (item_number_is_rule_number (ritem[off]))
             {
-              bitsetv lookahead = red->lookahead_tokens;
+              bitsetv lookahead = red->lookaheads;
               if (lookahead)
                 state_items[sidx].lookahead = lookahead[rule_search_idx];
               ++rule_search_idx;
@@ -211,7 +211,7 @@ init_trans (void)
       for (int j = 0; j < t->num; ++j)
         if (!TRANSITION_IS_DISABLED (t, j))
           hash_xinsert (transition_set, t->states[j]);
-      for (int j = state_item_map[i]; j < state_item_map[i + 1]; ++j)
+      for (state_item_number j = state_item_map[i]; j < state_item_map[i + 1]; ++j)
         {
           item_number *item = state_items[j].item;
           if (item_number_is_rule_number (*item))
@@ -222,16 +222,14 @@ init_trans (void)
           // find the item in the destination state that corresponds
           // to the transition of item
           for (int k = 0; k < dst->nitems; ++k)
-            {
+            if (item + 1 == ritem + dst->items[k])
-              if (item + 1 == ritem + dst->items[k])
+              {
-                {
+                state_item_number dstSI =
-                  state_item_number dstSI =
+                  state_item_index_lookup (dst->number, k);
-                    state_item_index_lookup (dst->number, k);
 
-                  state_items[j].trans = dstSI;
+                state_items[j].trans = dstSI;
-                  bitset_set (state_items[dstSI].revs, j);
+                bitset_set (state_items[dstSI].revs, j);
-                  break;
+                break;
-                }
             }
         }
       hash_free (transition_set);
@@ -250,10 +248,10 @@ init_prods (void)
 
       // Add the nitems of state to skip to the production portion
       // of that state's state_items
-      for (int j = state_item_map[i] + s->nitems;
+      for (state_item_number j = state_item_map[i] + s->nitems;
            j < state_item_map[i + 1]; ++j)
         {
-          state_item *src = state_items + j;
+          state_item *src = &state_items[j];
           item_number *item = src->item;
           symbol_number lhs = item_rule (item)->lhs->number;
           bitset itms = hash_pair_lookup (closure_map, lhs);
@@ -266,9 +264,9 @@ init_prods (void)
         }
       // For each item with a dot followed by a nonterminal,
       // try to create a production edge.
-      for (int j = state_item_map[i]; j < state_item_map[i + 1]; ++j)
+      for (state_item_number j = state_item_map[i]; j < state_item_map[i + 1]; ++j)
         {
-          state_item *src = state_items + j;
+          state_item *src = &state_items[j];
           item_number item = *(src->item);
           // Skip reduce items and items with terminals after the dot
           if (item_number_is_rule_number (item) || ISTOKEN (item))
@@ -301,12 +299,12 @@ gen_lookaheads (void)
 {
   for (state_item_number i = 0; i < nstate_items; ++i)
     {
-      state_item *si = state_items + i;
+      state_item *si = &state_items[i];
       if (item_number_is_symbol_number (*(si->item)) || !si->lookahead)
         continue;
 
       bitset lookahead = si->lookahead;
-      gl_list_t queue =
+      state_item_list queue =
         gl_list_create (GL_LINKED_LIST, NULL, NULL, NULL, true, 1,
                         (const void **) &si);
 
@@ -339,7 +337,7 @@ init_firsts (void)
   firsts = bitsetv_create (nnterms, nsyms, BITSET_FIXED);
   for (rule_number i = 0; i < nrules; ++i)
     {
-      rule *r = rules + i;
+      rule *r = &rules[i];
       item_number *n = r->rhs;
       // Iterate through nullable nonterminals to try to find a terminal.
       while (item_number_is_symbol_number (*n) && ISVAR (*n)
@@ -357,7 +355,7 @@ init_firsts (void)
       change = false;
       for (rule_number i = 0; i < nrules; ++i)
         {
-          rule *r = rules + i;
+          rule *r = &rules[i];
           symbol_number lhs = r->lhs->number;
           bitset f_lhs = FIRSTS (lhs);
           for (item_number *n = r->rhs;
@@ -392,7 +390,7 @@ disable_state_item (state_item *si)
 static void
 prune_forward (const state_item *si)
 {
-  gl_list_t queue =
+  state_item_list queue =
     gl_list_create (GL_LINKED_LIST, NULL, NULL, NULL, true, 1,
                     (const void **) &si);
 
@@ -401,7 +399,7 @@ prune_forward (const state_item *si)
       state_item *dsi = (state_item *) gl_list_get_at (queue, 0);
       gl_list_remove_at (queue, 0);
       if (dsi->trans >= 0)
-        gl_list_add_last (queue, state_items + dsi->trans);
+        gl_list_add_last (queue, &state_items[dsi->trans]);
 
       if (dsi->prods)
         {
@@ -409,7 +407,7 @@ prune_forward (const state_item *si)
           state_item_number sin;
           BITSET_FOR_EACH (biter, dsi->prods, sin, 0)
             {
-              const state_item *prod = state_items + sin;
+              const state_item *prod = &state_items[sin];
               bitset_reset (prod->revs, dsi - state_items);
               if (bitset_empty_p (prod->revs))
                 gl_list_add_last (queue, prod);
@@ -427,7 +425,7 @@ prune_forward (const state_item *si)
 static void
 prune_backward (const state_item *si)
 {
-  gl_list_t queue =
+  state_item_list queue =
     gl_list_create (GL_LINKED_LIST, NULL, NULL, NULL, true, 1,
                     (const void **) &si);
 
@@ -441,7 +439,7 @@ prune_backward (const state_item *si)
         {
           if (SI_DISABLED (sin))
             continue;
-          state_item *rev = state_items + sin;
+          state_item *rev = &state_items[sin];
           if (rev->prods)
             {
               bitset_reset (rev->prods, dsi - state_items);
@@ -466,7 +464,7 @@ prune_disabled_paths (void)
 {
   for (int i = nstate_items - 1; i >= 0; --i)
     {
-      state_item *si = state_items + i;
+      state_item *si = &state_items[i];
       if (si->trans == -1 && item_number_is_symbol_number (*si->item))
         {
           prune_forward (si);
@@ -494,9 +492,9 @@ state_items_report (void)
   for (state_number i = 0; i < nstates; ++i)
     {
       printf ("State %d:\n", i);
-      for (int j = state_item_map[i]; j < state_item_map[i + 1]; ++j)
+      for (state_item_number j = state_item_map[i]; j < state_item_map[i + 1]; ++j)
         {
-          state_item *si = state_items + j;
+          state_item *si = &state_items[j];
           item_print (si->item, NULL, stdout);
           if (SI_DISABLED (j))
             {
@@ -508,7 +506,7 @@ state_items_report (void)
           if (si->trans >= 0)
             {
               fputs ("    -> ", stdout);
-              print_state_item (state_items + si->trans, stdout, "");
+              print_state_item (&state_items[si->trans], stdout, "");
             }
 
           bitset sets[2] = { si->prods, si->revs };
@@ -523,7 +521,7 @@ state_items_report (void)
                   BITSET_FOR_EACH (biter, b, sin, 0)
                     {
                       fputs (txt[seti], stdout);
-                      print_state_item (state_items + sin, stdout, "");
+                      print_state_item (&state_items[sin], stdout, "");
                     }
                 }
             }
@@ -562,10 +560,10 @@ state_items_init (void)
 void
 state_items_free (void)
 {
-  for (int i = 0; i < nstate_items; ++i)
+  for (state_item_number i = 0; i < nstate_items; ++i)
     if (!SI_DISABLED (i))
       {
-        state_item *si = state_items + i;
+        state_item *si = &state_items[i];
         if (si->prods)
           bitset_free (si->prods);
         bitset_free (si->revs);
@@ -594,5 +592,5 @@ production_allowed (const state_item *si, const state_item *next)
       if (prec1 == prec2 && s1->assoc == left_assoc)
         return false;
     }
-    return true;
+  return true;
 }

src/state-item.h

@@ -28,16 +28,16 @@
 # include "state.h"
 
 /* Initializes a graph connecting (state, production item) pairs to
-   pairs they can make a transition or production step to. This graph
+   pairs they can make a transition or production step to.  This graph
    is used to search for paths that represent counterexamples of some
    conflict.
 
    state_items is an array of state state-item pairs ordered by state.
    state_item_map maps state numbers to the first item which
-   corresponds to it in the array. A state's portion in state_items
+   corresponds to it in the array.  A state's portion in state_items
-   begins with its items in the same order as it was in the
+   begins with its items in the same order as it was in the state.
-   state. This is then followed by productions from the closure of the
+   This is then followed by productions from the closure of the state
-   state in order by rule.
+   in order by rule.
 
    There are two type of edges in this graph transitions and
    productions.  Transitions are the same as transitions from the
@@ -53,9 +53,9 @@
    production edges, and all others will have reverse transition
    edges. */
 
-# define SI_DISABLED(sin) (state_items[sin].trans == -2)
+# define SI_DISABLED(Sin) (state_items[Sin].trans == -2)
-# define SI_PRODUCTION(si) ((si) == state_items || *((si)->item - 1) < 0)
+# define SI_PRODUCTION(Si) ((Si) == state_items || *((Si)->item - 1) < 0)
-# define SI_TRANSITION(si) ((si) != state_items && *((si)->item - 1) >= 0)
+# define SI_TRANSITION(Si) ((Si) != state_items && *((Si)->item - 1) >= 0)
 
 typedef int state_item_number;
 
@@ -69,6 +69,9 @@ typedef struct
   bitset lookahead;
 } state_item;
 
+// A path of state-items.
+typedef gl_list_t state_item_list;
+
 extern bitsetv firsts;
 # define FIRSTS(sym) firsts[(sym) - ntokens]
 
@@ -92,6 +95,7 @@ void state_items_free (void);
 
 bool production_allowed (const state_item *si, const state_item *next);
 
+// Iterating on a state_item_list.
 static inline bool
 state_item_list_next (gl_list_iterator_t *it, state_item **si)
 {

src/state.c

@@ -101,7 +101,7 @@ reductions_new (int num, rule **reds)
   size_t rules_size = num * sizeof *reds;
   reductions *res = xmalloc (offsetof (reductions, rules) + rules_size);
   res->num = num;
-  res->lookahead_tokens = NULL;
+  res->lookaheads = NULL;
   memcpy (res->rules, reds, rules_size);
   return res;
 }
@@ -260,20 +260,20 @@ state_errs_set (state *s, int num, symbol **tokens)
 `--------------------------------------------------*/
 
 void
-state_rule_lookahead_tokens_print (state const *s, rule const *r, FILE *out)
+state_rule_lookaheads_print (state const *s, rule const *r, FILE *out)
 {
   /* Find the reduction we are handling.  */
   reductions *reds = s->reductions;
   int red = state_reduction_find (s, r);
 
   /* Print them if there are.  */
-  if (reds->lookahead_tokens && red != -1)
+  if (reds->lookaheads && red != -1)
     {
       bitset_iterator biter;
       int k;
       char const *sep = "";
       fprintf (out, "  [");
-      BITSET_FOR_EACH (biter, reds->lookahead_tokens[red], k, 0)
+      BITSET_FOR_EACH (biter, reds->lookaheads[red], k, 0)
         {
           fprintf (out, "%s%s", sep, symbols[k]->tag);
           sep = ", ";
@@ -283,7 +283,7 @@ state_rule_lookahead_tokens_print (state const *s, rule const *r, FILE *out)
 }
 
 void
-state_rule_lookahead_tokens_print_xml (state const *s, rule const *r,
+state_rule_lookaheads_print_xml (state const *s, rule const *r,
                                        FILE *out, int level)
 {
   /* Find the reduction we are handling.  */
@@ -291,12 +291,12 @@ state_rule_lookahead_tokens_print_xml (state const *s, rule const *r,
   int red = state_reduction_find (s, r);
 
   /* Print them if there are.  */
-  if (reds->lookahead_tokens && red != -1)
+  if (reds->lookaheads && red != -1)
     {
       bitset_iterator biter;
       int k;
       xml_puts (out, level, "<lookaheads>");
-      BITSET_FOR_EACH (biter, reds->lookahead_tokens[red], k, 0)
+      BITSET_FOR_EACH (biter, reds->lookaheads[red], k, 0)
         {
           xml_printf (out, level + 1, "<symbol>%s</symbol>",
                       xml_escape (symbols[k]->tag));

src/state.h

@@ -62,7 +62,7 @@
 
    Each reductions structure describes the possible reductions at the
    state whose number is in the number field.  rules is an array of
-   num rules.  lookahead_tokens is an array of bitsets, one per rule.
+   num rules.  lookaheads is an array of bitsets, one per rule.
 
    Conflict resolution can decide that certain tokens in certain
    states should explicitly be errors (for implementing %nonassoc).
@@ -187,7 +187,7 @@ errs *errs_new (int num, symbol **tokens);
 typedef struct
 {
   int num;
-  bitset *lookahead_tokens;
+  bitset *lookaheads;
   /* Sorted ascendingly on rule number.  */
   rule *rules[1];
 } reductions;
@@ -254,9 +254,9 @@ void state_errs_set (state *s, int num, symbol **errors);
 
 /* Print on OUT all the lookahead tokens such that this STATE wants to
    reduce R.  */
-void state_rule_lookahead_tokens_print (state const *s, rule const *r, FILE *out);
+void state_rule_lookaheads_print (state const *s, rule const *r, FILE *out);
-void state_rule_lookahead_tokens_print_xml (state const *s, rule const *r,
+void state_rule_lookaheads_print_xml (state const *s, rule const *r,
-                                            FILE *out, int level);
+                                      FILE *out, int level);
 
 /* Create/destroy the states hash table.  */
 void state_hash_new (void);

src/tables.c

@@ -200,7 +200,7 @@ conflict_row (state *s)
         /* Find all reductions for token J, and record all that do not
            match ACTROW[J].  */
         for (int i = 0; i < reds->num; i += 1)
-          if (bitset_test (reds->lookahead_tokens[i], j)
+          if (bitset_test (reds->lookaheads[i], j)
               && (actrow[j]
                   != rule_number_as_item_number (reds->rules[i]->number)))
             {
@@ -247,7 +247,7 @@ action_row (state *s)
 
   reductions *reds = s->reductions;
   bool conflicted = false;
-  if (reds->lookahead_tokens)
+  if (reds->lookaheads)
     /* loop over all the rules available here which require
        lookahead (in reverse order to give precedence to the first
        rule) */
@@ -257,7 +257,7 @@ action_row (state *s)
       {
         bitset_iterator biter;
         int j;
-        BITSET_FOR_EACH (biter, reds->lookahead_tokens[i], j, 0)
+        BITSET_FOR_EACH (biter, reds->lookaheads[i], j, 0)
           {
             /* and record this rule as the rule to use if that
                token follows.  */
@@ -308,7 +308,7 @@ action_row (state *s)
     }
 
   /* Turn off default reductions where requested by the user.  See
-     state_lookahead_tokens_count in lalr.c to understand when states are
+     state_lookaheads_count in lalr.c to understand when states are
      labeled as consistent.  */
   {
     char *default_reductions =

tests/conflicts.at

@@ -726,7 +726,7 @@ AT_BISON_OPTION_POPDEFS
 AT_BISON_CHECK([[-Dlr.type=canonical-lr -o input.c input.y]],
                [[0]], [[]],
 [[input.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
-input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+input.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([[input]])
 AT_PARSER_CHECK([[input]], [[1]], [[]],
@@ -737,7 +737,7 @@ AT_PARSER_CHECK([[input]], [[1]], [[]],
 AT_BISON_CHECK([[-Dlr.type=canonical-lr -Dparse.lac=full \
                  -o input.c input.y]], [[0]], [[]],
 [[input.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
-input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+input.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([[input]])
 AT_PARSER_CHECK([[input]], [[1]], [[]],
@@ -748,7 +748,7 @@ AT_PARSER_CHECK([[input]], [[1]], [[]],
 AT_BISON_CHECK([[-Dlr.type=ielr -Dparse.lac=full -o input.c input.y]],
                [[0]], [[]],
 [[input.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
-input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+input.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([[input]])
 AT_PARSER_CHECK([[input]], [[1]], [[]],
@@ -773,7 +773,7 @@ exp: exp OP exp | NUM;
 
 AT_BISON_CHECK([-o input.c --report=all input.y], 0, [],
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
-input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+input.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 
 # Check the contents of the report.
@@ -861,12 +861,18 @@ State 5
     OP        [reduce using rule 1 (exp)]
     $default  reduce using rule 1 (exp)
 
-    Shift/reduce conflict on token OP:
+    shift/reduce conflict on token OP:
         1 exp: exp OP exp .
         1 exp: exp . OP exp
-      Example                  exp OP exp . OP exp
+      Example: exp OP exp . OP exp
-      First derivation         exp ::=[ exp ::=[ exp OP exp . ] OP exp ]
+      Shift derivation
-      Second derivation        exp ::=[ exp OP exp ::=[ exp . OP exp ] ]
+        exp
+        `-> exp OP exp
+                   `-> exp . OP exp
+      Reduce derivation
+        exp
+        `-> exp              OP exp
+            `-> exp OP exp .
 
 ]])
 
@@ -1026,7 +1032,7 @@ cond:
 
 AT_BISON_CHECK([-o input.c input.y], 0, [],
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
-input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+input.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 input.y:12.3-18: warning: rule useless in parser due to conflicts [-Wother]
 ]])
 
@@ -1119,7 +1125,7 @@ m4_popdef([AT_TEST])
 # else.
 
 AT_SETUP([Defaulted Conflicted Reduction])
-AT_KEYWORDS([report])
+AT_KEYWORDS([cex report])
 
 AT_DATA([input.y],
 [[%%
@@ -1131,7 +1137,7 @@ id : '0';
 
 AT_BISON_CHECK([-o input.c --report=all input.y], 0, [],
 [[input.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
-input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+input.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 input.y:4.6-8: warning: rule useless in parser due to conflicts [-Wother]
 ]])
 
@@ -1203,12 +1209,18 @@ State 1
     $end      [reduce using rule 4 (id)]
     $default  reduce using rule 3 (num)
 
-    Reduce/reduce conflict on token $end:
+    reduce/reduce conflict on token $end:
         3 num: '0' .
         4 id: '0' .
-      Example                  '0' .
+      Example: '0' .
-      First derivation         exp ::=[ num ::=[ '0' . ] ]
+      First reduce derivation
-      Second derivation        exp ::=[ id ::=[ '0' . ] ]
+        exp
+        `-> num
+            `-> '0' .
+      Second reduce derivation
+        exp
+        `-> id
+            `-> '0' .
 
 
 
@@ -1260,7 +1272,7 @@ exp: exp OP exp | NUM;
 
 AT_BISON_CHECK([-o input.c input.y], 1, [],
 [[input.y: error: shift/reduce conflicts: 1 found, 0 expected
-input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+input.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_CLEANUP
 
@@ -1297,7 +1309,7 @@ exp: exp OP exp | NUM;
 
 AT_BISON_CHECK([-o input.c input.y], 1, [],
 [[input.y: error: shift/reduce conflicts: 1 found, 2 expected
-input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+input.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_CLEANUP
 
@@ -1317,7 +1329,7 @@ a: 'a';
 
 AT_BISON_CHECK([-o input.c input.y], 1, [],
 [[input.y: error: reduce/reduce conflicts: 1 found, 0 expected
-input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+input.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_CLEANUP
 
@@ -1518,7 +1530,7 @@ e:   e '+' e
 
 AT_BISON_CHECK([-Wall -o input.c input.y], 0, [],
 [[input.y: warning: 4 shift/reduce conflicts [-Wconflicts-sr]
-input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+input.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 input.y:1.1-5: warning: useless precedence and associativity for '+' [-Wprecedence]
 input.y:2.1-5: warning: useless precedence and associativity for '*' [-Wprecedence]
 ]])
@@ -1579,6 +1591,8 @@ AT_CLEANUP
 
 AT_SETUP([[Unreachable States After Conflict Resolution]])
 
+AT_KEYWORDS([cex report])
+
 # If conflict resolution makes states unreachable, remove those states, report
 # rules that are then unused, and don't report conflicts in those states.  Test
 # what happens when a nonterminal becomes useless as a result of state removal
@@ -1624,7 +1638,7 @@ reported_conflicts:
 AT_BISON_CHECK([[--report=all input.y]], 0, [],
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
 input.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
-input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+input.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 input.y:12.5-20: warning: rule useless in parser due to conflicts [-Wother]
 input.y:20.5-20: warning: rule useless in parser due to conflicts [-Wother]
 input.y:21.4: warning: rule useless in parser due to conflicts [-Wother]
@@ -1750,21 +1764,33 @@ State 4
 
     reported_conflicts  go to state 6
 
-    Shift/reduce conflict on token 'a':
+    shift/reduce conflict on token 'a':
        10 reported_conflicts: . %empty
         8 reported_conflicts: . 'a'
-      First example            resolved_conflict . 'a'
+      First example: resolved_conflict . 'a' 'a'
-      First derivation         start ::=[ resolved_conflict reported_conflicts ::=[ . ] 'a' ]
+      Shift derivation
-      Second example           resolved_conflict . 'a' 'a'
+        start
-      Second derivation        start ::=[ resolved_conflict reported_conflicts ::=[ . 'a' ] 'a' ]
+        `-> resolved_conflict reported_conflicts 'a'
+                              `-> . 'a'
+      Second example: resolved_conflict . 'a'
+      Reduce derivation
+        start
+        `-> resolved_conflict reported_conflicts 'a'
+                              `-> .
 
-    Shift/reduce conflict on token 'a':
+    shift/reduce conflict on token 'a':
        10 reported_conflicts: . %empty
         9 reported_conflicts: . 'a'
-      First example            resolved_conflict . 'a'
+      First example: resolved_conflict . 'a' 'a'
-      First derivation         start ::=[ resolved_conflict reported_conflicts ::=[ . ] 'a' ]
+      Shift derivation
-      Second example           resolved_conflict . 'a' 'a'
+        start
-      Second derivation        start ::=[ resolved_conflict reported_conflicts ::=[ . 'a' ] 'a' ]
+        `-> resolved_conflict reported_conflicts 'a'
+                              `-> . 'a'
+      Second example: resolved_conflict . 'a'
+      Reduce derivation
+        start
+        `-> resolved_conflict reported_conflicts 'a'
+                              `-> .
 
 
 
@@ -1777,12 +1803,16 @@ State 5
     'a'       [reduce using rule 9 (reported_conflicts)]
     $default  reduce using rule 8 (reported_conflicts)
 
-    Reduce/reduce conflict on token 'a':
+    reduce/reduce conflict on token 'a':
         8 reported_conflicts: 'a' .
         9 reported_conflicts: 'a' .
-      Example                  'a' .
+      Example: 'a' .
-      First derivation         reported_conflicts ::=[ 'a' . ]
+      First reduce derivation
-      Second derivation        reported_conflicts ::=[ 'a' . ]
+        reported_conflicts
+        `-> 'a' .
+      Second reduce derivation
+        reported_conflicts
+        `-> 'a' .
 
 
 
@@ -1808,7 +1838,7 @@ AT_CHECK([[cat input.y >> input-keep.y]])
 AT_BISON_CHECK([[input-keep.y]], 0, [],
 [[input-keep.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
 input-keep.y: warning: 2 reduce/reduce conflicts [-Wconflicts-rr]
-input-keep.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+input-keep.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 input-keep.y:22.4: warning: rule useless in parser due to conflicts [-Wother]
 input-keep.y:26.16: warning: rule useless in parser due to conflicts [-Wother]
 input-keep.y:32.5-7: warning: rule useless in parser due to conflicts [-Wother]
@@ -1904,6 +1934,8 @@ AT_CLEANUP
 
 AT_SETUP([[%nonassoc error actions for multiple reductions in a state]])
 
+AT_KEYWORDS([cex report])
+
 AT_DATA([[input.y]],
 [[%nonassoc 'a' 'b' 'c'
 %%
@@ -1961,12 +1993,18 @@ AT_CHECK([[cat input.output | sed -n '/^State 0$/,/^State 1$/p']], 0,
     Conflict between rule 10 and token 'b' resolved as an error (%nonassoc 'b').
     Conflict between rule 11 and token 'c' resolved as an error (%nonassoc 'c').
 
-    Reduce/reduce conflict on token 'c':
+    reduce/reduce conflict on token 'c':
        12 empty_c2: . %empty
        13 empty_c3: . %empty
-      Example                  . 'c'
+      Example: . 'c'
-      First derivation         start ::=[ empty_c2 ::=[ . ] 'c' ]
+      First reduce derivation
-      Second derivation        start ::=[ empty_c3 ::=[ . ] 'c' ]
+        start
+        `-> empty_c2 'c'
+            `-> .
+      Second reduce derivation
+        start
+        `-> empty_c3 'c'
+            `-> .
 
 
 
@@ -2000,7 +2038,7 @@ exp: 'a' | 'a';
 AT_BISON_CHECK([[2.y]], [[0]], [],
 [[2.y: warning: %expect-rr applies only to GLR parsers [-Wother]
 2.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
-2.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+2.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 2.y:3.12-14: warning: rule useless in parser due to conflicts [-Wother]
 ]])
 
@@ -2037,15 +2075,14 @@ B: ;
 AT_BISON_CHECK([[sr-rr.y]], [[0]], [[]],
 [[sr-rr.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
 sr-rr.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
-sr-rr.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+sr-rr.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_BISON_CHECK([[-Wno-conflicts-sr sr-rr.y]], [[0]], [[]],
 [[sr-rr.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
-sr-rr.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+sr-rr.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_BISON_CHECK([[-Wno-conflicts-rr sr-rr.y]], [[0]], [[]],
 [[sr-rr.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
-sr-rr.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
 ]])
 
 [
@@ -2102,19 +2139,30 @@ for gram in sr-rr sr rr; do
         ]AT_BISON_CHECK([[-Werror $file]])[
       else
         {
+          issue_note=false
           if test -z "$sr_exp_i" && test "$sr_count" -ne 0; then
             echo "warning: $sr_count shift/reduce conflicts"
+            issue_note=true
           elif test "$sr_exp_i" -ne "$sr_count"; then
             echo "error: shift/reduce conflicts: $sr_count found, $sr_exp_i expected"
+            if test "$sr_count" -ne 0; then
+              issue_note=true
+            fi
           fi
           if test -z "$rr_exp_i" && test "$rr_count" -ne 0; then
             echo "warning: $rr_count reduce/reduce conflicts"
+            issue_note=true
           elif test "$rr_exp_i" -ne "$rr_count"; then
             echo "error: reduce/reduce conflicts: $rr_count found, $rr_exp_i expected"
+            if test "$rr_count" -ne 0; then
+              issue_note=true
+            fi
+          fi
+          if $issue_note; then
+            echo "note: rerun with option '-Wcounterexamples' to generate conflict counterexamples"
           fi
         } | sed -e "s/^/$file: /" > experr
         ]AT_BISON_CHECK([[-Wnone $file]], [[1]], [[]], [[experr]])[
-        echo "$file: error: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Werror=other]" >> experr
         ]AT_BISON_CHECK([[-Werror $file]], [[1]], [[]], [[experr]])[
       fi
     done

tests/counterexample.at

@@ -17,13 +17,23 @@
 
 AT_BANNER([[Counterexamples.]])
 
+# AT_BISON_CHECK_CEX(TREE, FLAT)
+# ------------------------------
 m4_define([AT_BISON_CHECK_CEX],
-[AT_DATA([experr], [$4])
+[AT_KEYWORDS([cex])
-sed -e ['s/time limit exceeded: [0-9][.0-9]*/time limit exceeded: XXX/g'] \
+
-  experr >expout
+AT_BISON_CHECK([-Wcounterexamples input.y], [0], [], [stderr])
-AT_BISON_CHECK([-Wcounterexamples $1], [$2], [$3], [stderr])
+# FIXME: Avoid trailing white spaces.
+AT_CHECK([[sed -e 's/time limit exceeded: [0-9][.0-9]*/time limit exceeded: XXX/g;s/ *$//;' stderr]],
+         [], [$1])
+
+m4_pushdef([AT_SET_ENV_IF],
+           [[YYFLAT=1; export YYFLAT;]]m4_defn([AT_SET_ENV_IF]))
+AT_BISON_CHECK([-Wcounterexamples input.y], [0], [], [stderr])
 AT_CHECK([[sed -e 's/time limit exceeded: [0-9][.0-9]*/time limit exceeded: XXX/g' stderr]],
-         [], [expout])
+         [], [$2])
+m4_popdef([AT_SET_ENV_IF])
+
 ])
 
 ## --------------------- ##
@@ -31,7 +41,6 @@ AT_CHECK([[sed -e 's/time limit exceeded: [0-9][.0-9]*/time limit exceeded: XXX/
 ## --------------------- ##
 
 AT_SETUP([Unifying S/R])
-AT_KEYWORDS([cex])
 
 AT_DATA([[input.y]],
 [[%token A B C
@@ -43,13 +52,25 @@ x: B | B C;
 y: A | A B;
 ]])
 
-AT_BISON_CHECK_CEX([input.y], [], [],
+AT_BISON_CHECK_CEX(
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
-Shift/reduce conflict on token B:
+input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
-  Example              A . B C
+  Example: A . B C
-  First derivation     s ::=[ a ::=[ A . ] x ::=[ B C ] ]
+  Shift derivation
-  Second derivation    s ::=[ y ::=[ A . B ] c ::=[ C ] ]
+    s
-
+    `-> y         c
+        `-> A . B `-> C
+  Reduce derivation
+    s
+    `-> a       x
+        `-> A . `-> B C
+input.y:4.4: warning: rule useless in parser due to conflicts [-Wother]
+]],
+[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
+input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
+  Example           A . B C
+  Shift derivation  s -> [ y -> [ A . B ] c -> [ C ] ]
+  Reduce derivation s -> [ a -> [ A . ] x -> [ B C ] ]
 input.y:4.4: warning: rule useless in parser due to conflicts [-Wother]
 ]])
 
@@ -60,7 +81,6 @@ AT_CLEANUP
 ## ------------------- ##
 
 AT_SETUP([Deep Unifying S/R])
-AT_KEYWORDS([cex])
 
 AT_DATA([[input.y]],
 [[%token A B C
@@ -72,18 +92,46 @@ a: A | A a;
 bc: B bc C | B C;
 ]])
 
-AT_BISON_CHECK_CEX([input.y], [], [],
+AT_BISON_CHECK_CEX(
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
-Shift/reduce conflict on token B:
+input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
-  Example              A . B C
+  Example: A . B C
-  First derivation     s ::=[ a ::=[ A . ] bc ::=[ B C ] ]
+  Shift derivation
-  Second derivation    s ::=[ ac ::=[ A ac ::=[ b ::=[ . B ] ] C ] ]
+    s
-
+    `-> ac
-Shift/reduce conflict on token B:
+        `-> A ac          C
-  Example              A A . B B C C
+              `-> b
-  First derivation     s ::=[ a ::=[ A a ::=[ A . ] ] bc ::=[ B bc ::=[ B C ] C ] ]
+                  `-> . B
-  Second derivation    s ::=[ ac ::=[ A ac ::=[ A ac ::=[ b ::=[ . b ::=[ B B ] ] ] C ] C ] ]
+  Reduce derivation
-
+    s
+    `-> a       bc
+        `-> A . `-> B C
+input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
+  Example: A A . B B C C
+  Shift derivation
+    s
+    `-> ac
+        `-> A ac                        C
+              `-> A ac                C
+                    `-> b
+                        `-> . b
+                              `-> B B
+  Reduce derivation
+    s
+    `-> a             bc
+        `-> A a       `-> B bc      C
+              `-> A .       `-> B C
+input.y:6.4: warning: rule useless in parser due to conflicts [-Wother]
+]],
+[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
+input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
+  Example           A . B C
+  Shift derivation  s -> [ ac -> [ A ac -> [ b -> [ . B ] ] C ] ]
+  Reduce derivation s -> [ a -> [ A . ] bc -> [ B C ] ]
+input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
+  Example           A A . B B C C
+  Shift derivation  s -> [ ac -> [ A ac -> [ A ac -> [ b -> [ . b -> [ B B ] ] ] C ] C ] ]
+  Reduce derivation s -> [ a -> [ A a -> [ A . ] ] bc -> [ B bc -> [ B C ] C ] ]
 input.y:6.4: warning: rule useless in parser due to conflicts [-Wother]
 ]])
 
@@ -94,7 +142,6 @@ AT_CLEANUP
 ## ------------------------------------ ##
 
 AT_SETUP([S/R Conflict with Nullable Symbols])
-AT_KEYWORDS([cex])
 
 AT_DATA([[input.y]],
 [[%token A B X Y
@@ -107,19 +154,47 @@ y: %empty | Y y;
 xby: B | X xby Y;
 ]])
 
-AT_BISON_CHECK_CEX([input.y], [], [],
+AT_BISON_CHECK_CEX(
 [[input.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
-Shift/reduce conflict on token B:
+input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
-  Example              A . B
+  Example: A . B
-  First derivation     s ::=[ ax ::=[ A x ::=[ . ] ] by ::=[ B y ::=[ ] ] ]
+  Shift derivation
-  Second derivation    s ::=[ A xby ::=[ . B ] ]
+    s
-
+    `-> A xby
-Shift/reduce conflict on token B:
+          `-> . B
-  First example        A X . B y $end
+  Reduce derivation
-  First derivation     $accept ::=[ s ::=[ ax ::=[ A x ::=[ X x ::=[ . ] ] ] by ::=[ B y ] ] $end ]
+    s
-  Second example       A X . B Y $end
+    `-> ax          by
-  Second derivation    $accept ::=[ s ::=[ A xby ::=[ X xby ::=[ . B ] Y ] ] $end ]
+        `-> A x     `-> B y
-
+              `-> .       `-> %empty
+input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
+  First example: A X . B Y $end
+  Shift derivation
+    $accept
+    `-> s                     $end
+        `-> A xby
+              `-> X xby     Y
+                    `-> . B
+  Second example: A X . B y $end
+  Reduce derivation
+    $accept
+    `-> s                             $end
+        `-> ax                by
+            `-> A x           `-> B y
+                  `-> X x
+                        `-> .
+input.y:5.4-9: warning: rule useless in parser due to conflicts [-Wother]
+]],
+[[input.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
+input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
+  Example           A . B
+  Shift derivation  s -> [ A xby -> [ . B ] ]
+  Reduce derivation s -> [ ax -> [ A x -> [ . ] ] by -> [ B y -> [ ] ] ]
+input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
+  First example     A X . B Y $end
+  Shift derivation  $accept -> [ s -> [ A xby -> [ X xby -> [ . B ] Y ] ] $end ]
+  Second example    A X . B y $end
+  Reduce derivation $accept -> [ s -> [ ax -> [ A x -> [ X x -> [ . ] ] ] by -> [ B y ] ] $end ]
 input.y:5.4-9: warning: rule useless in parser due to conflicts [-Wother]
 ]])
 
@@ -130,7 +205,6 @@ AT_CLEANUP
 ## ---------------------------- ##
 
 AT_SETUP([Non-unifying Ambiguous S/R])
-AT_KEYWORDS([cex])
 
 AT_DATA([[input.y]],
 [[%token A B C D E
@@ -143,14 +217,31 @@ cd: C D;
 bc: B C;
 ]])
 
-AT_BISON_CHECK_CEX([input.y], [], [],
+AT_BISON_CHECK_CEX(
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
-Shift/reduce conflict on token C:
+input.y: warning: shift/reduce conflict on token C [-Wcounterexamples]
-  First example        B . C D $end
+  First example: B . C $end
-  First derivation     $accept ::=[ g ::=[ x ::=[ b ::=[ B . ] cd ::=[ C D ] ] ] $end ]
+  Shift derivation
-  Second example       B . C $end
+    $accept
-  Second derivation    $accept ::=[ g ::=[ x ::=[ bc ::=[ B . C ] ] ] $end ]
+    `-> g                 $end
-
+        `-> x
+            `-> bc
+                `-> B . C
+  Second example: B . C D $end
+  Reduce derivation
+    $accept
+    `-> g                       $end
+        `-> x
+            `-> b       cd
+                `-> B . `-> C D
+input.y:6.4: warning: rule useless in parser due to conflicts [-Wother]
+]],
+[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
+input.y: warning: shift/reduce conflict on token C [-Wcounterexamples]
+  First example     B . C $end
+  Shift derivation  $accept -> [ g -> [ x -> [ bc -> [ B . C ] ] ] $end ]
+  Second example    B . C D $end
+  Reduce derivation $accept -> [ g -> [ x -> [ b -> [ B . ] cd -> [ C D ] ] ] $end ]
 input.y:6.4: warning: rule useless in parser due to conflicts [-Wother]
 ]])
 
@@ -161,7 +252,6 @@ AT_CLEANUP
 ## ------------------------------ ##
 
 AT_SETUP([Non-unifying Unambiguous S/R])
-AT_KEYWORDS([cex])
 
 AT_DATA([[input.y]],
 [[%token A B
@@ -172,14 +262,31 @@ x: A;
 y: A A B;
 ]])
 
-AT_BISON_CHECK_CEX([input.y], [], [],
+AT_BISON_CHECK_CEX(
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
-Shift/reduce conflict on token A:
+input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
-  First example        A . A $end
+  First example: A . A B $end
-  First derivation     $accept ::=[ s ::=[ s ::=[ t ::=[ x ::=[ A . ] ] ] t ::=[ x ::=[ A ] ] ] $end ]
+  Shift derivation
-  Second example       A . A B $end
+    $accept
-  Second derivation    $accept ::=[ s ::=[ t ::=[ y ::=[ A . A B ] ] ] $end ]
+    `-> s                   $end
-
+        `-> t
+            `-> y
+                `-> A . A B
+  Second example: A . A $end
+  Reduce derivation
+    $accept
+    `-> s                             $end
+        `-> s               t
+            `-> t           `-> x
+                `-> x           `-> A
+                    `-> A .
+]],
+[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
+input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
+  First example     A . A B $end
+  Shift derivation  $accept -> [ s -> [ t -> [ y -> [ A . A B ] ] ] $end ]
+  Second example    A . A $end
+  Reduce derivation $accept -> [ s -> [ s -> [ t -> [ x -> [ A . ] ] ] t -> [ x -> [ A ] ] ] $end ]
 ]])
 
 AT_CLEANUP
@@ -189,7 +296,6 @@ AT_CLEANUP
 ## ----------------------- ##
 
 AT_SETUP([S/R after first token])
-AT_KEYWORDS([cex])
 
 AT_DATA([[input.y]],
 [[%token A B X Y
@@ -205,19 +311,45 @@ xy: X Y;
 y: Y;
 ]])
 
-AT_BISON_CHECK_CEX([input.y], [], [],
+AT_BISON_CHECK_CEX(
 [[input.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
-Shift/reduce conflict on token A:
+input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
-  Example              b . A X X Y
+  Example: b . A X X Y
-  First derivation     a ::=[ r ::=[ b . ] t ::=[ A x ::=[ X ] xy ::=[ X Y ] ] ]
+  Shift derivation
-  Second derivation    a ::=[ s ::=[ b . xx ::=[ A X X ] y ::=[ Y ] ] ]
+    a
-
+    `-> s
-Shift/reduce conflict on token X:
+        `-> b . xx        y
-  First example        X . X xy
+                `-> A X X `-> Y
-  First derivation     a ::=[ x ::=[ X . ] t ::=[ X xy ] ]
+  Reduce derivation
-  Second example       A X . X
+    a
-  Second derivation    a ::=[ t ::=[ A xx ::=[ X . X ] ] ]
+    `-> r       t
-
+        `-> b . `-> A x     xy
+                      `-> X `-> X Y
+input.y: warning: shift/reduce conflict on token X [-Wcounterexamples]
+  First example: A X . X
+  Shift derivation
+    a
+    `-> t
+        `-> A xx
+              `-> X . X
+  Second example: X . X xy
+  Reduce derivation
+    a
+    `-> x       t
+        `-> X . `-> X xy
+input.y:4.4: warning: rule useless in parser due to conflicts [-Wother]
+input.y:8.4: warning: rule useless in parser due to conflicts [-Wother]
+]],
+[[input.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
+input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
+  Example           b . A X X Y
+  Shift derivation  a -> [ s -> [ b . xx -> [ A X X ] y -> [ Y ] ] ]
+  Reduce derivation a -> [ r -> [ b . ] t -> [ A x -> [ X ] xy -> [ X Y ] ] ]
+input.y: warning: shift/reduce conflict on token X [-Wcounterexamples]
+  First example     A X . X
+  Shift derivation  a -> [ t -> [ A xx -> [ X . X ] ] ]
+  Second example    X . X xy
+  Reduce derivation a -> [ x -> [ X . ] t -> [ X xy ] ]
 input.y:4.4: warning: rule useless in parser due to conflicts [-Wother]
 input.y:8.4: warning: rule useless in parser due to conflicts [-Wother]
 ]])
@@ -229,7 +361,6 @@ AT_CLEANUP
 ## ----------------------------- ##
 
 AT_SETUP([Unifying R/R counterexample])
-AT_KEYWORDS([cex])
 
 AT_DATA([[input.y]],
 [[%token A
@@ -238,13 +369,24 @@ a : A b ;
 b : A | b;
 ]])
 
-AT_BISON_CHECK_CEX([input.y], [], [],
+AT_BISON_CHECK_CEX(
 [[input.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
-Reduce/reduce conflict on token $end:
+input.y: warning: reduce/reduce conflict on token $end [-Wcounterexamples]
-  Example              A b .
+  Example: A b .
-  First derivation     a ::=[ A b . ]
+  First reduce derivation
-  Second derivation    a ::=[ A b ::=[ b . ] ]
+    a
-
+    `-> A b .
+  Second reduce derivation
+    a
+    `-> A b
+          `-> b .
+input.y:4.9: warning: rule useless in parser due to conflicts [-Wother]
+]],
+[[input.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
+input.y: warning: reduce/reduce conflict on token $end [-Wcounterexamples]
+  Example                  A b .
+  First reduce derivation  a -> [ A b . ]
+  Second reduce derivation a -> [ A b -> [ b . ] ]
 input.y:4.9: warning: rule useless in parser due to conflicts [-Wother]
 ]])
 
@@ -255,7 +397,6 @@ AT_CLEANUP
 ## --------------------------------- ##
 
 AT_SETUP([Non-unifying R/R LR(1) conflict])
-AT_KEYWORDS([cex])
 
 AT_DATA([[input.y]],
 [[%token A B C D
@@ -265,14 +406,29 @@ a: D;
 b: D;
 ]])
 
-AT_BISON_CHECK_CEX([input.y], [], [],
+AT_BISON_CHECK_CEX(
 [[input.y: warning: 2 reduce/reduce conflicts [-Wconflicts-rr]
-Reduce/reduce conflict on tokens A, C:
+input.y: warning: reduce/reduce conflict on tokens A, C [-Wcounterexamples]
-  First example        D . A $end
+  First example: D . A $end
-  First derivation     $accept ::=[ s ::=[ a ::=[ D . ] A ] $end ]
+  First reduce derivation
-  Second example       B D . A $end
+    $accept
-  Second derivation    $accept ::=[ s ::=[ B b ::=[ D . ] A ] $end ]
+    `-> s             $end
-
+        `-> a       A
+            `-> D .
+  Second example: B D . A $end
+  Second reduce derivation
+    $accept
+    `-> s               $end
+        `-> B b       A
+              `-> D .
+input.y:5.4: warning: rule useless in parser due to conflicts [-Wother]
+]],
+[[input.y: warning: 2 reduce/reduce conflicts [-Wconflicts-rr]
+input.y: warning: reduce/reduce conflict on tokens A, C [-Wcounterexamples]
+  First example            D . A $end
+  First reduce derivation  $accept -> [ s -> [ a -> [ D . ] A ] $end ]
+  Second example           B D . A $end
+  Second reduce derivation $accept -> [ s -> [ B b -> [ D . ] A ] $end ]
 input.y:5.4: warning: rule useless in parser due to conflicts [-Wother]
 ]])
 
@@ -283,7 +439,6 @@ AT_CLEANUP
 ## --------------------------------- ##
 
 AT_SETUP([Non-unifying R/R LR(2) conflict])
-AT_KEYWORDS([cex])
 
 AT_DATA([[input.y]],
 [[%token H J K X
@@ -293,15 +448,31 @@ a: H i;
 i: X | i J K;
 ]])
 
-AT_BISON_CHECK_CEX([input.y], [], [],
+AT_BISON_CHECK_CEX(
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
-Shift/reduce conflict on token J:
+input.y: warning: shift/reduce conflict on token J [-Wcounterexamples]
 time limit exceeded: XXX
-  First example        H i . J $end
+  First example: H i . J K $end
-  First derivation     $accept ::=[ s ::=[ a ::=[ H i . ] J ] $end ]
+  Shift derivation
-  Second example       H i . J K $end
+    $accept
-  Second derivation    $accept ::=[ a ::=[ H i ::=[ i . J K ] ] $end ]
+    `-> a                 $end
-
+        `-> H i
+              `-> i . J K
+  Second example: H i . J $end
+  Reduce derivation
+    $accept
+    `-> s               $end
+        `-> a         J
+            `-> H i .
+input.y:4.4-6: warning: rule useless in parser due to conflicts [-Wother]
+]],
+[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
+input.y: warning: shift/reduce conflict on token J [-Wcounterexamples]
+time limit exceeded: XXX
+  First example     H i . J K $end
+  Shift derivation  $accept -> [ a -> [ H i -> [ i . J K ] ] $end ]
+  Second example    H i . J $end
+  Reduce derivation $accept -> [ s -> [ a -> [ H i . ] J ] $end ]
 input.y:4.4-6: warning: rule useless in parser due to conflicts [-Wother]
 ]])
 
@@ -315,7 +486,6 @@ AT_CLEANUP
 # graph search
 
 AT_SETUP([Cex Search Prepend])
-AT_KEYWORDS([cex])
 
 AT_DATA([[input.y]],
 [[%token N A B C D
@@ -326,18 +496,45 @@ a: A;
 b: A B C | A B D;
 ]])
 
-AT_BISON_CHECK_CEX([input.y], [], [],
+AT_BISON_CHECK_CEX(
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
-Shift/reduce conflict on token B:
+input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
-  Example              N A . B C
+  Example: N A . B C
-  First derivation     s ::=[ n ::=[ N a ::=[ A . ] B ] C ]
+  Shift derivation
-  Second derivation    s ::=[ n ::=[ N b ::=[ A . B C ] ] ]
+    s
-
+    `-> n
-Shift/reduce conflict on token B:
+        `-> N b
-  Example              N N A . B D C
+              `-> A . B C
-  First derivation     s ::=[ n ::=[ N n ::=[ N a ::=[ A . ] B ] D ] C ]
+  Reduce derivation
-  Second derivation    s ::=[ n ::=[ N n ::=[ N b ::=[ A . B D ] ] C ] ]
+    s
-
+    `-> n               C
+        `-> N a       B
+              `-> A .
+input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
+  Example: N N A . B D C
+  Shift derivation
+    s
+    `-> n
+        `-> N n                 C
+              `-> N b
+                    `-> A . B D
+  Reduce derivation
+    s
+    `-> n                       C
+        `-> N n               D
+              `-> N a       B
+                    `-> A .
+input.y:5.4: warning: rule useless in parser due to conflicts [-Wother]
+]],
+[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
+input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
+  Example           N A . B C
+  Shift derivation  s -> [ n -> [ N b -> [ A . B C ] ] ]
+  Reduce derivation s -> [ n -> [ N a -> [ A . ] B ] C ]
+input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
+  Example           N N A . B D C
+  Shift derivation  s -> [ n -> [ N n -> [ N b -> [ A . B D ] ] C ] ]
+  Reduce derivation s -> [ n -> [ N n -> [ N a -> [ A . ] B ] D ] C ]
 input.y:5.4: warning: rule useless in parser due to conflicts [-Wother]
 ]])
 
@@ -351,7 +548,6 @@ AT_CLEANUP
 # precedence/associativity directives work.
 
 AT_SETUP([R/R cex with prec])
-AT_KEYWORDS([cex])
 
 AT_DATA([[input.y]],
 [[%left b
@@ -363,18 +559,46 @@ B : A b A;
 C : A c A;
 ]])
 
-AT_BISON_CHECK_CEX([input.y], [], [],
+AT_BISON_CHECK_CEX(
 [[input.y: warning: 4 reduce/reduce conflicts [-Wconflicts-rr]
-Reduce/reduce conflict on tokens b, c:
+input.y: warning: reduce/reduce conflict on tokens b, c [-Wcounterexamples]
-  Example              B . b c
+  Example: B . b c
-  First derivation     S ::=[ B ::=[ A ::=[ B . ] b A ::=[ ] ] C ::=[ A ::=[ ] c A ::=[ ] ] ]
+  First reduce derivation
-  Second derivation    S ::=[ B C ::=[ A ::=[ B ::=[ A ::=[ . ] b A ::=[ ] ] ] c A ::=[ ] ] ]
+    S
-
+    `-> B                        C
-Reduce/reduce conflict on tokens b, c:
+        `-> A       b A          `-> A          c A
-  Example              C . c b
+            `-> B .   `-> %empty     `-> %empty   `-> %empty
-  First derivation     S ::=[ C ::=[ A ::=[ C . ] c A ::=[ ] ] B ::=[ A ::=[ ] b A ::=[ ] ] ]
+  Second reduce derivation
-  Second derivation    S ::=[ C B ::=[ A ::=[ C ::=[ A ::=[ . ] c A ::=[ ] ] ] b A ::=[ ] ] ]
+    S
-
+    `-> B C
+          `-> A                          c A
+              `-> B                        `-> %empty
+                  `-> A     b A
+                      `-> .   `-> %empty
+input.y: warning: reduce/reduce conflict on tokens b, c [-Wcounterexamples]
+  Example: C . c b
+  First reduce derivation
+    S
+    `-> C                        B
+        `-> A       c A          `-> A          b A
+            `-> C .   `-> %empty     `-> %empty   `-> %empty
+  Second reduce derivation
+    S
+    `-> C B
+          `-> A                          b A
+              `-> C                        `-> %empty
+                  `-> A     c A
+                      `-> .   `-> %empty
+]],
+[[input.y: warning: 4 reduce/reduce conflicts [-Wconflicts-rr]
+input.y: warning: reduce/reduce conflict on tokens b, c [-Wcounterexamples]
+  Example                  B . b c
+  First reduce derivation  S -> [ B -> [ A -> [ B . ] b A -> [ ] ] C -> [ A -> [ ] c A -> [ ] ] ]
+  Second reduce derivation S -> [ B C -> [ A -> [ B -> [ A -> [ . ] b A -> [ ] ] ] c A -> [ ] ] ]
+input.y: warning: reduce/reduce conflict on tokens b, c [-Wcounterexamples]
+  Example                  C . c b
+  First reduce derivation  S -> [ C -> [ A -> [ C . ] c A -> [ ] ] B -> [ A -> [ ] b A -> [ ] ] ]
+  Second reduce derivation S -> [ C B -> [ A -> [ C -> [ A -> [ . ] c A -> [ ] ] ] b A -> [ ] ] ]
 ]])
 
 AT_CLEANUP
@@ -384,7 +608,6 @@ AT_CLEANUP
 ## ------------------- ##
 
 AT_SETUP([Null nonterminals])
-AT_KEYWORDS([cex])
 
 AT_DATA([[input.y]],
 [[%token A
@@ -395,58 +618,172 @@ c : ;
 d : a | c A | d;
 ]])
 
-AT_BISON_CHECK_CEX([input.y], [], [],
+AT_BISON_CHECK_CEX(
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
 input.y: warning: 6 reduce/reduce conflicts [-Wconflicts-rr]
-Reduce/reduce conflict on token A:
+input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
-  First example        . c A A $end
+  First example: . c A A $end
-  First derivation     $accept ::=[ a ::=[ b ::=[ . ] d ::=[ c A A ] ] $end ]
+  First reduce derivation
-  Second example       . c A A $end
+    $accept
-  Second derivation    $accept ::=[ a ::=[ c ::=[ . ] d ::=[ c A A ] ] $end ]
+    `-> a                   $end
-
+        `-> b     d
-Reduce/reduce conflict on token A:
+            `-> . `-> c A A
+  Second example: . c A A $end
+  Second reduce derivation
+    $accept
+    `-> a                   $end
+        `-> c     d
+            `-> . `-> c A A
+input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
 time limit exceeded: XXX
-  First example        b . c A A $end
+  First example: b . c A A $end
-  First derivation     $accept ::=[ a ::=[ b d ::=[ a ::=[ b ::=[ . ] d ::=[ c A A ] ] ] ] $end ]
+  First reduce derivation
-  Second example       b . A $end
+    $accept
-  Second derivation    $accept ::=[ a ::=[ b d ::=[ c ::=[ . ] A ] ] $end ]
+    `-> a                             $end
-
+        `-> b d
-Reduce/reduce conflict on token A:
+              `-> a
+                  `-> b     d
+                      `-> . `-> c A A
+  Second example: b . A $end
+  Second reduce derivation
+    $accept
+    `-> a                 $end
+        `-> b d
+              `-> c     A
+                  `-> .
+input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
 time limit exceeded: XXX
-  First example        c . c A A $end
+  First example: c . c A A $end
-  First derivation     $accept ::=[ a ::=[ c d ::=[ a ::=[ b ::=[ . ] d ::=[ c A A ] ] ] ] $end ]
+  First reduce derivation
-  Second example       c . A $end
+    $accept
-  Second derivation    $accept ::=[ a ::=[ c d ::=[ c ::=[ . ] A ] ] $end ]
+    `-> a                             $end
-
+        `-> c d
-Shift/reduce conflict on token A:
+              `-> a
+                  `-> b     d
+                      `-> . `-> c A A
+  Second example: c . A $end
+  Second reduce derivation
+    $accept
+    `-> a                 $end
+        `-> c d
+              `-> c     A
+                  `-> .
+input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
 time limit exceeded: XXX
-  First example        b c . c A A $end
+  First example: b c . A
-  First derivation     $accept ::=[ a ::=[ b d ::=[ a ::=[ c d ::=[ a ::=[ b ::=[ . ] d ::=[ c A A ] ] ] ] ] ] $end ]
+  Shift derivation
-  Second example       b c . A
+    a
-  Second derivation    a ::=[ b d ::=[ c . A ] ]
+    `-> b d
-
+          `-> c . A
-Reduce/reduce conflict on token A:
+  Second example: b c . c A A $end
-  First example        b c . c A A $end
+  Reduce derivation
-  First derivation     $accept ::=[ a ::=[ b d ::=[ a ::=[ c d ::=[ a ::=[ b ::=[ . ] d ::=[ c A A ] ] ] ] ] ] $end ]
+    $accept
-  Second example       b c . A $end
+    `-> a                                       $end
-  Second derivation    $accept ::=[ a ::=[ b d ::=[ a ::=[ c d ::=[ c ::=[ . ] A ] ] ] ] $end ]
+        `-> b d
-
+              `-> a
-Shift/reduce conflict on token A:
+                  `-> c d
-  First example        b c . A $end
+                        `-> a
-  First derivation     $accept ::=[ a ::=[ b d ::=[ a ::=[ c d ::=[ c ::=[ . ] A ] ] ] ] $end ]
+                            `-> b     d
-  Second example       b c . A
+                                `-> . `-> c A A
-  Second derivation    a ::=[ b d ::=[ c . A ] ]
+input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
-
+  First example: b c . c A A $end
-Reduce/reduce conflict on token $end:
+  First reduce derivation
-  Example              b d .
+    $accept
-  First derivation     a ::=[ b d . ]
+    `-> a                                       $end
-  Second derivation    a ::=[ b d ::=[ d . ] ]
+        `-> b d
-
+              `-> a
-Reduce/reduce conflict on token $end:
+                  `-> c d
-  Example              c d .
+                        `-> a
-  First derivation     a ::=[ c d . ]
+                            `-> b     d
-  Second derivation    a ::=[ c d ::=[ d . ] ]
+                                `-> . `-> c A A
-
+  Second example: b c . A $end
+  Second reduce derivation
+    $accept
+    `-> a                           $end
+        `-> b d
+              `-> a
+                  `-> c d
+                        `-> c     A
+                            `-> .
+input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
+  First example: b c . A
+  Shift derivation
+    a
+    `-> b d
+          `-> c . A
+  Second example: b c . A $end
+  Reduce derivation
+    $accept
+    `-> a                           $end
+        `-> b d
+              `-> a
+                  `-> c d
+                        `-> c     A
+                            `-> .
+input.y: warning: reduce/reduce conflict on token $end [-Wcounterexamples]
+  Example: b d .
+  First reduce derivation
+    a
+    `-> b d .
+  Second reduce derivation
+    a
+    `-> b d
+          `-> d .
+input.y: warning: reduce/reduce conflict on token $end [-Wcounterexamples]
+  Example: c d .
+  First reduce derivation
+    a
+    `-> c d .
+  Second reduce derivation
+    a
+    `-> c d
+          `-> d .
+input.y:5.4: warning: rule useless in parser due to conflicts [-Wother]
+input.y:6.15: warning: rule useless in parser due to conflicts [-Wother]
+]],
+[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
+input.y: warning: 6 reduce/reduce conflicts [-Wconflicts-rr]
+input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
+  First example            . c A A $end
+  First reduce derivation  $accept -> [ a -> [ b -> [ . ] d -> [ c A A ] ] $end ]
+  Second example           . c A A $end
+  Second reduce derivation $accept -> [ a -> [ c -> [ . ] d -> [ c A A ] ] $end ]
+input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
+time limit exceeded: XXX
+  First example            b . c A A $end
+  First reduce derivation  $accept -> [ a -> [ b d -> [ a -> [ b -> [ . ] d -> [ c A A ] ] ] ] $end ]
+  Second example           b . A $end
+  Second reduce derivation $accept -> [ a -> [ b d -> [ c -> [ . ] A ] ] $end ]
+input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
+time limit exceeded: XXX
+  First example            c . c A A $end
+  First reduce derivation  $accept -> [ a -> [ c d -> [ a -> [ b -> [ . ] d -> [ c A A ] ] ] ] $end ]
+  Second example           c . A $end
+  Second reduce derivation $accept -> [ a -> [ c d -> [ c -> [ . ] A ] ] $end ]
+input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
+time limit exceeded: XXX
+  First example     b c . A
+  Shift derivation  a -> [ b d -> [ c . A ] ]
+  Second example    b c . c A A $end
+  Reduce derivation $accept -> [ a -> [ b d -> [ a -> [ c d -> [ a -> [ b -> [ . ] d -> [ c A A ] ] ] ] ] ] $end ]
+input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
+  First example            b c . c A A $end
+  First reduce derivation  $accept -> [ a -> [ b d -> [ a -> [ c d -> [ a -> [ b -> [ . ] d -> [ c A A ] ] ] ] ] ] $end ]
+  Second example           b c . A $end
+  Second reduce derivation $accept -> [ a -> [ b d -> [ a -> [ c d -> [ c -> [ . ] A ] ] ] ] $end ]
+input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
+  First example     b c . A
+  Shift derivation  a -> [ b d -> [ c . A ] ]
+  Second example    b c . A $end
+  Reduce derivation $accept -> [ a -> [ b d -> [ a -> [ c d -> [ c -> [ . ] A ] ] ] ] $end ]
+input.y: warning: reduce/reduce conflict on token $end [-Wcounterexamples]
+  Example                  b d .
+  First reduce derivation  a -> [ b d . ]
+  Second reduce derivation a -> [ b d -> [ d . ] ]
+input.y: warning: reduce/reduce conflict on token $end [-Wcounterexamples]
+  Example                  c d .
+  First reduce derivation  a -> [ c d . ]
+  Second reduce derivation a -> [ c d -> [ d . ] ]
 input.y:5.4: warning: rule useless in parser due to conflicts [-Wother]
 input.y:6.15: warning: rule useless in parser due to conflicts [-Wother]
 ]])
@@ -458,7 +795,6 @@ AT_CLEANUP
 ## --------------------------- ##
 
 AT_SETUP([Non-unifying Prefix Share])
-AT_KEYWORDS([cex])
 
 # Tests for a counterexample which should start its derivation
 # at a shared symbol rather than the start symbol.
@@ -471,13 +807,26 @@ a: H i J J
 i: %empty | i J;
 ]])
 
-AT_BISON_CHECK_CEX([input.y], [], [],
+AT_BISON_CHECK_CEX(
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
-Shift/reduce conflict on token J:
+input.y: warning: shift/reduce conflict on token J [-Wcounterexamples]
-  Example              H i J . J J
+  Example: H i J . J J
-  First derivation     s ::=[ a ::=[ H i ::=[ i J . ] J J ] ]
+  Shift derivation
-  Second derivation    s ::=[ a ::=[ H i J . J ] J ]
+    s
-
+    `-> a             J
+        `-> H i J . J
+  Reduce derivation
+    s
+    `-> a
+        `-> H i         J J
+              `-> i J .
+input.y:5.13-15: warning: rule useless in parser due to conflicts [-Wother]
+]],
+[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
+input.y: warning: shift/reduce conflict on token J [-Wcounterexamples]
+  Example           H i J . J J
+  Shift derivation  s -> [ a -> [ H i J . J ] J ]
+  Reduce derivation s -> [ a -> [ H i -> [ i J . ] J J ] ]
 input.y:5.13-15: warning: rule useless in parser due to conflicts [-Wother]
 ]])
 
@@ -491,7 +840,6 @@ AT_CLEANUP
 # are derived correctly.
 
 AT_SETUP([Deep Null Unifying])
-AT_KEYWORDS([cex])
 
 AT_DATA([[input.y]],
 [[%token A D
@@ -503,13 +851,26 @@ c: %empty
 d: D;
 ]])
 
-AT_BISON_CHECK_CEX([input.y], [], [],
+AT_BISON_CHECK_CEX(
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
-Shift/reduce conflict on token D:
+input.y: warning: shift/reduce conflict on token D [-Wcounterexamples]
-  Example              A a . D
+  Example: A a . D
-  First derivation     s ::=[ A a a ::=[ b ::=[ c ::=[ . ] ] ] d ::=[ D ] ]
+  Shift derivation
-  Second derivation    s ::=[ A a d ::=[ . D ] ]
+    s
-
+    `-> A a d
+            `-> . D
+  Reduce derivation
+    s
+    `-> A a a             d
+            `-> b         `-> D
+                `-> c
+                    `-> .
+]],
+[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
+input.y: warning: shift/reduce conflict on token D [-Wcounterexamples]
+  Example           A a . D
+  Shift derivation  s -> [ A a d -> [ . D ] ]
+  Reduce derivation s -> [ A a a -> [ b -> [ c -> [ . ] ] ] d -> [ D ] ]
 ]])
 
 AT_CLEANUP
@@ -521,7 +882,6 @@ AT_CLEANUP
 # Tests that expand_to_conflict works with nullable sybols
 
 AT_SETUP([Deep Null Non-unifying])
-AT_KEYWORDS([cex])
 
 AT_DATA([[input.y]],
 [[%token A D E
@@ -533,14 +893,30 @@ c: %empty
 d: D;
 ]])
 
-AT_BISON_CHECK_CEX([input.y], [], [],
+AT_BISON_CHECK_CEX(
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
-Shift/reduce conflict on token D:
+input.y: warning: shift/reduce conflict on token D [-Wcounterexamples]
-  First example        A a . D E $end
+  First example: A a . D $end
-  First derivation     $accept ::=[ s ::=[ A a a ::=[ b ::=[ c ::=[ . ] ] ] d ::=[ D ] E ] $end ]
+  Shift derivation
-  Second example       A a . D $end
+    $accept
-  Second derivation    $accept ::=[ s ::=[ A a d ::=[ . D ] ] $end ]
+    `-> s               $end
-
+        `-> A a d
+                `-> . D
+  Second example: A a . D E $end
+  Reduce derivation
+    $accept
+    `-> s                             $end
+        `-> A a a             d     E
+                `-> b         `-> D
+                    `-> c
+                        `-> .
+]],
+[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
+input.y: warning: shift/reduce conflict on token D [-Wcounterexamples]
+  First example     A a . D $end
+  Shift derivation  $accept -> [ s -> [ A a d -> [ . D ] ] $end ]
+  Second example    A a . D E $end
+  Reduce derivation $accept -> [ s -> [ A a a -> [ b -> [ c -> [ . ] ] ] d -> [ D ] E ] $end ]
 ]])
 
 AT_CLEANUP

tests/diagnostics.at

@@ -28,6 +28,8 @@ m4_pushdef([AT_TEST],
 AT_SETUP([$1])
 AT_KEYWORDS([diagnostics])
 
+m4_if(m4_index([$1], [Counterexample]), [-1], [], [AT_KEYWORDS([cex])])
+
 # We need UTF-8 support for correct screen-width computation of UTF-8
 # characters.  Skip the test if not available.
 locale=`locale -a | $EGREP '^en_US\.(UTF-8|utf8)$' | sed 1q`
@@ -49,7 +51,7 @@ if $EGREP ['\^M|\\[0-9][0-9][0-9]'] input.y experr >/dev/null; then
   AT_PERL_REQUIRE([-pi -e 's{\^M}{\r}g;s{\\(\d{3}|.)}{$v = $[]1; $v =~ /\A\d+\z/ ? chr($v) : $v}ge' input.y experr])
 fi
 
-AT_CHECK([LC_ALL="$locale" $5 bison -fcaret --color=debug -Wall,cex input.y], [$3], [], [experr])
+AT_CHECK(AT_SET_ENV [LC_ALL="$locale" $5 bison -fcaret --color=debug -Wall,cex input.y], [$3], [], [experr])
 
 # When no style, same messages, but without style.
 # Except for the second display of the counterexample,
@@ -66,7 +68,7 @@ AT_PERL_REQUIRE([-pi -e '
 # Cannot use AT_BISON_CHECK easily as we need to change the
 # environment.
 # FIXME: Enhance AT_BISON_CHECK.
-AT_CHECK([LC_ALL="$locale" $5 bison -fcaret -Wall,cex input.y], [$3], [], [experr])
+AT_CHECK(AT_SET_ENV [LC_ALL="$locale" $5 bison -fcaret -Wall,cex input.y], [$3], [], [experr])
 
 
 AT_BISON_OPTION_POPDEFS
@@ -533,34 +535,111 @@ exp
 ]],
 [1],
 [[input.y: <error>error:</error> shift/reduce conflicts: 4 found, 0 expected
-Shift/reduce conflict on token "+":
+input.y: <warning>warning:</warning> shift/reduce conflict on token "+" [<warning>-Wcounterexamples</warning>]
-  Example              <cex-0><cex-1><cex-leaf>exp</cex-leaf> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-0>
+  Example: <cex-0><cex-leaf>exp</cex-leaf> <cex-leaf>"+"</cex-leaf><cex-1> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-1></cex-0>
-  First derivation     <cex-0><cex-step>exp ::=[ </cex-step><cex-1><cex-step>exp ::=[ </cex-step><cex-leaf>exp</cex-leaf> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot><cex-step> ]</cex-step></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-0>
+  Shift derivation
-  Example              <cex-0><cex-leaf>exp</cex-leaf> <cex-leaf>"+"</cex-leaf><cex-1> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-1></cex-0>
+    <cex-0><cex-step>exp</cex-step></cex-0>
-  Second derivation    <cex-0><cex-step>exp ::=[ </cex-step><cex-leaf>exp</cex-leaf> <cex-leaf>"+"</cex-leaf><cex-1> <cex-step>exp ::=[ </cex-step><cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-1><cex-step> ]</cex-step></cex-0>
+    <cex-0><cex-step>↳ <cex-leaf>exp</cex-leaf><cex-leaf> "+"</cex-leaf><cex-1><cex-step> exp</cex-step></cex-1></cex-step></cex-0>
-
+    <cex-1><cex-step>          ↳ <cex-leaf>exp</cex-leaf><cex-dot> •</cex-dot><cex-leaf> "+"</cex-leaf><cex-leaf> exp</cex-leaf></cex-step></cex-1>
-Shift/reduce conflict on token "else":
+  Example: <cex-0><cex-1><cex-leaf>exp</cex-leaf> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-0>
-  Example              <cex-0><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf><cex-1> <cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot></cex-1> <cex-leaf>"else"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-0>
+  Reduce derivation
-  First derivation     <cex-0><cex-step>exp ::=[ </cex-step><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf><cex-1> <cex-step>exp ::=[ </cex-step><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot><cex-step> ]</cex-step></cex-1> <cex-leaf>"else"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-0>
+    <cex-0><cex-step>exp</cex-step></cex-0>
-  Example              <cex-0><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf><cex-1> <cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot> <cex-leaf>"else"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-1></cex-0>
+    <cex-0><cex-step>↳ <cex-1><cex-step>exp</cex-step></cex-1><cex-leaf>             "+"</cex-leaf><cex-leaf> exp</cex-leaf></cex-step></cex-0>
-  Second derivation    <cex-0><cex-step>exp ::=[ </cex-step><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf><cex-1> <cex-step>exp ::=[ </cex-step><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot> <cex-leaf>"else"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-1><cex-step> ]</cex-step></cex-0>
+    <cex-1><cex-step>  ↳ <cex-leaf>exp</cex-leaf><cex-leaf> "+"</cex-leaf><cex-leaf> exp</cex-leaf><cex-dot> •</cex-dot></cex-step></cex-1>
-
+input.y: <warning>warning:</warning> shift/reduce conflict on token "else" [<warning>-Wcounterexamples</warning>]
-Shift/reduce conflict on token "+":
+  Example: <cex-0><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf><cex-1> <cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot> <cex-leaf>"else"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-1></cex-0>
-  Example              <cex-0><cex-1><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-0>
+  Shift derivation
-  First derivation     <cex-0><cex-step>exp ::=[ </cex-step><cex-1><cex-step>exp ::=[ </cex-step><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot><cex-step> ]</cex-step></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-0>
+    <cex-0><cex-step>exp</cex-step></cex-0>
-  Example              <cex-0><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf><cex-1> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-1></cex-0>
+    <cex-0><cex-step>↳ <cex-leaf>"if"</cex-leaf><cex-leaf> exp</cex-leaf><cex-leaf> "then"</cex-leaf><cex-1><cex-step> exp</cex-step></cex-1></cex-step></cex-0>
-  Second derivation    <cex-0><cex-step>exp ::=[ </cex-step><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf><cex-1> <cex-step>exp ::=[ </cex-step><cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-1><cex-step> ]</cex-step></cex-0>
+    <cex-1><cex-step>                  ↳ <cex-leaf>"if"</cex-leaf><cex-leaf> exp</cex-leaf><cex-leaf> "then"</cex-leaf><cex-leaf> exp</cex-leaf><cex-dot> •</cex-dot><cex-leaf> "else"</cex-leaf><cex-leaf> exp</cex-leaf></cex-step></cex-1>
-
+  Example: <cex-0><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf><cex-1> <cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot></cex-1> <cex-leaf>"else"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-0>
-Shift/reduce conflict on token "+":
+  Reduce derivation
-  Example              <cex-0><cex-1><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"else"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-0>
+    <cex-0><cex-step>exp</cex-step></cex-0>
-  First derivation     <cex-0><cex-step>exp ::=[ </cex-step><cex-1><cex-step>exp ::=[ </cex-step><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"else"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot><cex-step> ]</cex-step></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-0>
+    <cex-0><cex-step>↳ <cex-leaf>"if"</cex-leaf><cex-leaf> exp</cex-leaf><cex-leaf> "then"</cex-leaf><cex-1><cex-step> exp</cex-step></cex-1><cex-leaf>                     "else"</cex-leaf><cex-leaf> exp</cex-leaf></cex-step></cex-0>
-  Example              <cex-0><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"else"</cex-leaf><cex-1> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-1></cex-0>
+    <cex-1><cex-step>                  ↳ <cex-leaf>"if"</cex-leaf><cex-leaf> exp</cex-leaf><cex-leaf> "then"</cex-leaf><cex-leaf> exp</cex-leaf><cex-dot> •</cex-dot></cex-step></cex-1>
-  Second derivation    <cex-0><cex-step>exp ::=[ </cex-step><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"else"</cex-leaf><cex-1> <cex-step>exp ::=[ </cex-step><cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-1><cex-step> ]</cex-step></cex-0>
+input.y: <warning>warning:</warning> shift/reduce conflict on token "+" [<warning>-Wcounterexamples</warning>]
-
+  Example: <cex-0><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf><cex-1> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-1></cex-0>
+  Shift derivation
+    <cex-0><cex-step>exp</cex-step></cex-0>
+    <cex-0><cex-step>↳ <cex-leaf>"if"</cex-leaf><cex-leaf> exp</cex-leaf><cex-leaf> "then"</cex-leaf><cex-1><cex-step> exp</cex-step></cex-1></cex-step></cex-0>
+    <cex-1><cex-step>                  ↳ <cex-leaf>exp</cex-leaf><cex-dot> •</cex-dot><cex-leaf> "+"</cex-leaf><cex-leaf> exp</cex-leaf></cex-step></cex-1>
+  Example: <cex-0><cex-1><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-0>
+  Reduce derivation
+    <cex-0><cex-step>exp</cex-step></cex-0>
+    <cex-0><cex-step>↳ <cex-1><cex-step>exp</cex-step></cex-1><cex-leaf>                     "+"</cex-leaf><cex-leaf> exp</cex-leaf></cex-step></cex-0>
+    <cex-1><cex-step>  ↳ <cex-leaf>"if"</cex-leaf><cex-leaf> exp</cex-leaf><cex-leaf> "then"</cex-leaf><cex-leaf> exp</cex-leaf><cex-dot> •</cex-dot></cex-step></cex-1>
+input.y: <warning>warning:</warning> shift/reduce conflict on token "+" [<warning>-Wcounterexamples</warning>]
+  Example: <cex-0><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"else"</cex-leaf><cex-1> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-1></cex-0>
+  Shift derivation
+    <cex-0><cex-step>exp</cex-step></cex-0>
+    <cex-0><cex-step>↳ <cex-leaf>"if"</cex-leaf><cex-leaf> exp</cex-leaf><cex-leaf> "then"</cex-leaf><cex-leaf> exp</cex-leaf><cex-leaf> "else"</cex-leaf><cex-1><cex-step> exp</cex-step></cex-1></cex-step></cex-0>
+    <cex-1><cex-step>                             ↳ <cex-leaf>exp</cex-leaf><cex-dot> •</cex-dot><cex-leaf> "+"</cex-leaf><cex-leaf> exp</cex-leaf></cex-step></cex-1>
+  Example: <cex-0><cex-1><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"else"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-0>
+  Reduce derivation
+    <cex-0><cex-step>exp</cex-step></cex-0>
+    <cex-0><cex-step>↳ <cex-1><cex-step>exp</cex-step></cex-1><cex-leaf>                                "+"</cex-leaf><cex-leaf> exp</cex-leaf></cex-step></cex-0>
+    <cex-1><cex-step>  ↳ <cex-leaf>"if"</cex-leaf><cex-leaf> exp</cex-leaf><cex-leaf> "then"</cex-leaf><cex-leaf> exp</cex-leaf><cex-leaf> "else"</cex-leaf><cex-leaf> exp</cex-leaf><cex-dot> •</cex-dot></cex-step></cex-1>
 ]])
 
 
+AT_TEST([[Deep Counterexamples]],
+[[%expect 0
+%%
+exp: x1 e1 foo1 x1 | y1 e2 bar1 y1
+foo1: foo2
+foo2: foo3
+foo3: x1 foo4
+foo4: "quuux"
 
+bar1: bar2
+bar2: bar3
+bar3: y1 bar4
+bar4: "quuux"
+
+x1: x2
+x2: x3
+x3: "X"
+
+y1: y2
+y2: y3
+y3: "X"
+
+e1:
+e2:
+]],
+[1],
+[[input.y:30.4: <warning>warning:</warning> empty rule without %empty [<warning>-Wempty-rule</warning>]
+   30 | e1:
+      |    <warning>^</warning>
+      |    <fixit-insert>%empty</fixit-insert>
+input.y:31.4: <warning>warning:</warning> empty rule without %empty [<warning>-Wempty-rule</warning>]
+   31 | e2:
+      |    <warning>^</warning>
+      |    <fixit-insert>%empty</fixit-insert>
+input.y: <error>error:</error> reduce/reduce conflicts: 1 found, 0 expected
+input.y: <warning>warning:</warning> reduce/reduce conflict on token "X" [<warning>-Wcounterexamples</warning>]
+  Example: <cex-0><cex-1><cex-2><cex-3><cex-leaf>"X"</cex-leaf> <cex-dot>•</cex-dot></cex-3></cex-2></cex-1><cex-4></cex-4><cex-5><cex-6><cex-7><cex-8><cex-9><cex-10> <cex-leaf>"X"</cex-leaf></cex-10></cex-9></cex-8><cex-11> <cex-leaf>"quuux"</cex-leaf></cex-11></cex-7></cex-6></cex-5><cex-12><cex-13><cex-14> <cex-leaf>"X"</cex-leaf></cex-14></cex-13></cex-12></cex-0>
+  First reduce derivation
+    <cex-0><cex-step>exp</cex-step></cex-0>
+    <cex-0><cex-step>↳ <cex-1><cex-step>x1</cex-step></cex-1><cex-4><cex-step>          e1</cex-step></cex-4><cex-5><cex-step>  foo1</cex-step></cex-5><cex-12><cex-step>                      x1</cex-step></cex-12></cex-step></cex-0>
+    <cex-1><cex-step>  ↳ <cex-2><cex-step>x2</cex-step></cex-2></cex-step></cex-1><cex-4><cex-step>        ↳ ε</cex-step></cex-4><cex-5><cex-step> ↳ <cex-6><cex-step>foo2</cex-step></cex-6></cex-step></cex-5><cex-12><cex-step>                    ↳ <cex-13><cex-step>x2</cex-step></cex-13></cex-step></cex-12>
+    <cex-2><cex-step>    ↳ <cex-3><cex-step>x3</cex-step></cex-3></cex-step></cex-2><cex-6><cex-step>            ↳ <cex-7><cex-step>foo3</cex-step></cex-7></cex-step></cex-6><cex-13><cex-step>                    ↳ <cex-14><cex-step>x3</cex-step></cex-14></cex-step></cex-13>
+    <cex-3><cex-step>      ↳ <cex-leaf>"X"</cex-leaf><cex-dot> •</cex-dot></cex-step></cex-3><cex-7><cex-step>         ↳ <cex-8><cex-step>x1</cex-step></cex-8><cex-11><cex-step>        foo4</cex-step></cex-11></cex-step></cex-7><cex-14><cex-step>          ↳ <cex-leaf>"X"</cex-leaf></cex-step></cex-14>
+    <cex-8><cex-step>                        ↳ <cex-9><cex-step>x2</cex-step></cex-9></cex-step></cex-8><cex-11><cex-step>      ↳ <cex-leaf>"quuux"</cex-leaf></cex-step></cex-11>
+    <cex-9><cex-step>                          ↳ <cex-10><cex-step>x3</cex-step></cex-10></cex-step></cex-9>
+    <cex-10><cex-step>                            ↳ <cex-leaf>"X"</cex-leaf></cex-step></cex-10>
+  Example: <cex-0><cex-1><cex-2><cex-3><cex-leaf>"X"</cex-leaf> <cex-dot>•</cex-dot></cex-3></cex-2></cex-1><cex-4></cex-4><cex-5><cex-6><cex-7><cex-8><cex-9><cex-10> <cex-leaf>"X"</cex-leaf></cex-10></cex-9></cex-8><cex-11> <cex-leaf>"quuux"</cex-leaf></cex-11></cex-7></cex-6></cex-5><cex-12><cex-13><cex-14> <cex-leaf>"X"</cex-leaf></cex-14></cex-13></cex-12></cex-0>
+  Second reduce derivation
+    <cex-0><cex-step>exp</cex-step></cex-0>
+    <cex-0><cex-step>↳ <cex-1><cex-step>y1</cex-step></cex-1><cex-4><cex-step>          e2</cex-step></cex-4><cex-5><cex-step>  bar1</cex-step></cex-5><cex-12><cex-step>                      y1</cex-step></cex-12></cex-step></cex-0>
+    <cex-1><cex-step>  ↳ <cex-2><cex-step>y2</cex-step></cex-2></cex-step></cex-1><cex-4><cex-step>        ↳ ε</cex-step></cex-4><cex-5><cex-step> ↳ <cex-6><cex-step>bar2</cex-step></cex-6></cex-step></cex-5><cex-12><cex-step>                    ↳ <cex-13><cex-step>y2</cex-step></cex-13></cex-step></cex-12>
+    <cex-2><cex-step>    ↳ <cex-3><cex-step>y3</cex-step></cex-3></cex-step></cex-2><cex-6><cex-step>            ↳ <cex-7><cex-step>bar3</cex-step></cex-7></cex-step></cex-6><cex-13><cex-step>                    ↳ <cex-14><cex-step>y3</cex-step></cex-14></cex-step></cex-13>
+    <cex-3><cex-step>      ↳ <cex-leaf>"X"</cex-leaf><cex-dot> •</cex-dot></cex-step></cex-3><cex-7><cex-step>         ↳ <cex-8><cex-step>y1</cex-step></cex-8><cex-11><cex-step>        bar4</cex-step></cex-11></cex-step></cex-7><cex-14><cex-step>          ↳ <cex-leaf>"X"</cex-leaf></cex-step></cex-14>
+    <cex-8><cex-step>                        ↳ <cex-9><cex-step>y2</cex-step></cex-9></cex-step></cex-8><cex-11><cex-step>      ↳ <cex-leaf>"quuux"</cex-leaf></cex-step></cex-11>
+    <cex-9><cex-step>                          ↳ <cex-10><cex-step>y3</cex-step></cex-10></cex-step></cex-9>
+    <cex-10><cex-step>                            ↳ <cex-leaf>"X"</cex-leaf></cex-step></cex-10>
+input.y: <warning>warning:</warning> fix-its can be applied.  Rerun with option '--update'. [<warning>-Wother</warning>]
+]])
 
 m4_popdef([AT_TEST])
 

tests/existing.at

@@ -434,7 +434,7 @@ input.y:323.10: warning: empty rule without %empty [-Wempty-rule]
 ]AT_COND_CASE([[canonical LR]],
 [[input.y: warning: 265 shift/reduce conflicts [-Wconflicts-sr]]],
 [[input.y: warning: 65 shift/reduce conflicts [-Wconflicts-sr]]])[
-input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+input.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 input.y:39.1-5: warning: useless associativity for FUNC_CALL, use %precedence [-Wprecedence]
 input.y:44.1-5: warning: useless associativity for YNUMBER, use %precedence [-Wprecedence]
 input.y:44.1-5: warning: useless associativity for YSTRING, use %precedence [-Wprecedence]
@@ -1419,7 +1419,7 @@ input.y:591.18: warning: empty rule without %empty [-Wempty-rule]
 input.y: warning: 144 reduce/reduce conflicts [-Wconflicts-rr]]],
 [[input.y: warning: 78 shift/reduce conflicts [-Wconflicts-sr]
 input.y: warning: 10 reduce/reduce conflicts [-Wconflicts-rr]]])[
-input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+input.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 input.y:72.1-5: warning: useless associativity for HQUA, use %precedence [-Wprecedence]
 input.y:53.1-6: warning: useless associativity for HASSIGN, use %precedence [-Wprecedence]
 input.y:54.1-5: warning: useless associativity for HORELSE, use %precedence [-Wprecedence]

tests/glr-regression.at

@@ -89,7 +89,7 @@ AT_BISON_OPTION_POPDEFS
 
 AT_BISON_CHECK([[-o glr-regr1.c -rall glr-regr1.y]], 0, [],
 [[glr-regr1.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
-glr-regr1.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+glr-regr1.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([glr-regr1])
 AT_PARSER_CHECK([[glr-regr1 BPBPB]], 0,
@@ -214,7 +214,7 @@ AT_BISON_OPTION_POPDEFS
 
 AT_BISON_CHECK([[-o glr-regr2a.c -rall glr-regr2a.y]], 0, [],
 [[glr-regr2a.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
-glr-regr2a.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+glr-regr2a.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([glr-regr2a])
 
@@ -350,7 +350,7 @@ AT_BISON_OPTION_POPDEFS
 AT_BISON_CHECK([[-o glr-regr3.c -rall glr-regr3.y]], 0, [],
 [[glr-regr3.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
 glr-regr3.y: warning: 2 reduce/reduce conflicts [-Wconflicts-rr]
-glr-regr3.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+glr-regr3.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([glr-regr3])
 
@@ -447,7 +447,7 @@ AT_BISON_OPTION_POPDEFS
 
 AT_BISON_CHECK([[-o glr-regr4.c -rall glr-regr4.y]], 0, [],
 [[glr-regr4.y: warning: 2 reduce/reduce conflicts [-Wconflicts-rr]
-glr-regr4.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+glr-regr4.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([glr-regr4])
 
@@ -505,7 +505,7 @@ AT_BISON_OPTION_POPDEFS
 
 AT_BISON_CHECK([[-o glr-regr5.c -rall glr-regr5.y]], 0, [],
 [[glr-regr5.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
-glr-regr5.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+glr-regr5.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([glr-regr5])
 
@@ -555,7 +555,7 @@ AT_BISON_OPTION_POPDEFS
 
 AT_BISON_CHECK([[-o glr-regr6.c -rall glr-regr6.y]], 0, [],
 [[glr-regr6.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
-glr-regr6.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+glr-regr6.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([glr-regr6])
 
@@ -646,7 +646,7 @@ AT_BISON_OPTION_POPDEFS
 
 AT_BISON_CHECK([[-o glr-regr7.c -rall glr-regr7.y]], 0, [],
 [[glr-regr7.y: warning: 2 reduce/reduce conflicts [-Wconflicts-rr]
-glr-regr7.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+glr-regr7.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([glr-regr7])
 
@@ -737,7 +737,7 @@ AT_BISON_OPTION_POPDEFS
 
 AT_BISON_CHECK([[-o glr-regr8.c -rall glr-regr8.y]], 0, [],
 [[glr-regr8.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
-glr-regr8.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+glr-regr8.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([glr-regr8])
 
@@ -819,7 +819,7 @@ AT_BISON_OPTION_POPDEFS
 
 AT_BISON_CHECK([[-o glr-regr9.c -rall glr-regr9.y]], 0, [],
 [[glr-regr9.y: warning: 2 reduce/reduce conflicts [-Wconflicts-rr]
-glr-regr9.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+glr-regr9.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([glr-regr9])
 
@@ -877,7 +877,7 @@ AT_BISON_OPTION_POPDEFS
 
 AT_BISON_CHECK([[-o glr-regr10.c -rall glr-regr10.y]], 0, [],
 [[glr-regr10.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
-glr-regr10.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+glr-regr10.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([glr-regr10])
 
@@ -937,7 +937,7 @@ AT_BISON_OPTION_POPDEFS
 
 AT_BISON_CHECK([[-o glr-regr11.c -rall glr-regr11.y]], 0, [],
 [[glr-regr11.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
-glr-regr11.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+glr-regr11.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([glr-regr11])
 
@@ -1060,7 +1060,7 @@ AT_BISON_OPTION_POPDEFS
 AT_BISON_CHECK([[-o glr-regr12.c -rall glr-regr12.y]], 0, [],
 [[glr-regr12.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
 glr-regr12.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
-glr-regr12.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+glr-regr12.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([glr-regr12])
 
@@ -1392,7 +1392,7 @@ AT_BISON_OPTION_POPDEFS
 
 AT_BISON_CHECK([[-o glr-regr14.c -rall glr-regr14.y]], 0, [],
 [[glr-regr14.y: warning: 5 reduce/reduce conflicts [-Wconflicts-rr]
-glr-regr14.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+glr-regr14.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([glr-regr14])
 
@@ -1487,7 +1487,7 @@ AT_BISON_OPTION_POPDEFS
 
 AT_BISON_CHECK([[-o glr-regr15.c -rall glr-regr15.y]], 0, [],
 [[glr-regr15.y: warning: 2 reduce/reduce conflicts [-Wconflicts-rr]
-glr-regr15.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+glr-regr15.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([glr-regr15])
 
@@ -1549,7 +1549,7 @@ AT_BISON_OPTION_POPDEFS
 
 AT_BISON_CHECK([[-o glr-regr16.c -rall glr-regr16.y]], 0, [],
 [[glr-regr16.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
-glr-regr16.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+glr-regr16.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([glr-regr16])
 
@@ -1625,7 +1625,7 @@ AT_BISON_OPTION_POPDEFS
 
 AT_BISON_CHECK([[-o glr-regr17.c -rall glr-regr17.y]], 0, [],
 [[glr-regr17.y: warning: 3 reduce/reduce conflicts [-Wconflicts-rr]
-glr-regr17.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+glr-regr17.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([glr-regr17])
 
@@ -1719,7 +1719,7 @@ d: /* nada.  */;
 
 AT_BISON_CHECK([[-o input.c input.y]], 0, [],
 [[input.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
-input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+input.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]])
 AT_COMPILE([input])
 

tests/input.at

@@ -2887,7 +2887,6 @@ input.y:13.1-14: note: previous definition
 input.y:14.16-29: warning: %define variable 'parse.error' redefined [-Wother]
 input.y:13.16-29: note: previous definition
 input.y: error: reduce/reduce conflicts: 0 found, 42 expected
-input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
 input.y: warning: fix-its can be applied.  Rerun with option '--update'. [-Wother]
 ]])
 

tests/local.at

@@ -1169,11 +1169,16 @@ m4_define([AT_BISON_CHECK_XML],
   [cp xml-tests/test.output expout]
   AT_CHECK([[$XSLTPROC \
              `]]AT_SET_ENV[[ bison --print-datadir`/xslt/xml2text.xsl \
-             xml-tests/test.xml]], [[0]], [expout])
+             xml-tests/test.xml]], [[0]], [stdout])
+  # xml2text and xml2dot always use '•', while --report uses '•' or '.'
+  # depending on the locale, and the test suite is run with the plain
+  # C locale.
+  AT_CHECK([[sed -e 's/•/./g' stdout]], [], [expout])
   [sort xml-tests/test.gv > expout]
   AT_CHECK([[$XSLTPROC \
              `]]AT_SET_ENV[[ bison --print-datadir`/xslt/xml2dot.xsl \
-             xml-tests/test.xml | sort]], [[0]], [expout])
+             xml-tests/test.xml | sort | sed -e 's/•/./g']],
+           [[0]], [stdout])
   [rm -rf xml-tests expout]
   AT_RESTORE_SPECIAL_FILES
 [fi]])
@@ -1194,7 +1199,7 @@ m4_define([AT_BISON_CHECK_XML],
 # The testsuite verbose output, at least, will be incorrect, but nothing may
 # fail to make sure you notice.
 m4_define([AT_SET_ENV_IF],
-[[[COLUMNS=1000; export COLUMNS;]] m4_null_if($1, [], [[[VALGRIND_OPTS="$VALGRIND_OPTS --leak-check=summary --show-reachable=no"; export VALGRIND_OPTS; ]]])])
+[[[COLUMNS=1000; export COLUMNS; NO_TERM_HYPERLINKS=1; export NO_TERM_HYPERLINKS;]] m4_null_if($1, [], [[[VALGRIND_OPTS="$VALGRIND_OPTS --leak-check=summary --show-reachable=no"; export VALGRIND_OPTS; ]]])])
 
 
 # AT_SET_ENV

tests/local.mk

@@ -36,6 +36,14 @@ $(top_srcdir)/%D%/package.m4: $(top_srcdir)/configure
 	} >$@.tmp
 	$(AM_V_at)mv $@.tmp $@
 
+
+# Update the test cases.  Consider the latest test results to be the
+# correct expectations, and change the test cases to match them.
+.PHONY: update-tests
+update-tests:
+	$(AM_V_GEN)cd $(top_srcdir) \
+	  && build-aux/update-test $(abs_builddir)/%D%/testsuite.dir/*/testsuite.log
+
 ## ------------------------- ##
 ## Generate the test suite.  ##
 ## ------------------------- ##

tests/reduce.at

@@ -1300,7 +1300,7 @@ dnl INPUT
 dnl BISON-STDERR
 [AT_COND_CASE([[LALR]],
 [[input.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
-input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+input.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 ]], [])],
 
 dnl TABLES

tests/report.at

@@ -764,24 +764,24 @@ AT_CHECK([[sed -e 's/bison-xml-report version="[^"]*"/bison-xml-report version="
       </rule>
     </rules>
     <terminals>
-      <terminal symbol-number="0" token-number="0" name="&quot;end of file&quot;" usefulness="useful"/>
+      <terminal symbol-number="0" token-number="0" name="&quot;end of file&quot;" type="" usefulness="useful"/>
-      <terminal symbol-number="1" token-number="256" name="error" usefulness="useful"/>
+      <terminal symbol-number="1" token-number="256" name="error" type="" usefulness="useful"/>
-      <terminal symbol-number="3" token-number="258" name="&quot;:=&quot;" usefulness="useful"/>
+      <terminal symbol-number="3" token-number="258" name="&quot;:=&quot;" type="" usefulness="useful"/>
-      <terminal symbol-number="4" token-number="259" name="&quot;incr&quot;" usefulness="useful"/>
+      <terminal symbol-number="4" token-number="259" name="&quot;incr&quot;" type="" usefulness="useful"/>
-      <terminal symbol-number="5" token-number="260" name="&quot;identifier&quot;" usefulness="useful"/>
+      <terminal symbol-number="5" token-number="260" name="&quot;identifier&quot;" type="std::string" usefulness="useful"/>
-      <terminal symbol-number="6" token-number="261" name="&quot;number&quot;" usefulness="useful"/>
+      <terminal symbol-number="6" token-number="261" name="&quot;number&quot;" type="int" usefulness="useful"/>
-      <terminal symbol-number="7" token-number="262" name="&quot;(&quot;" usefulness="useful"/>
+      <terminal symbol-number="7" token-number="262" name="&quot;(&quot;" type="" usefulness="useful"/>
-      <terminal symbol-number="8" token-number="263" name="&quot;)&quot;" usefulness="useful"/>
+      <terminal symbol-number="8" token-number="263" name="&quot;)&quot;" type="" usefulness="useful"/>
     </terminals>
     <nonterminals>
-      <nonterminal symbol-number="9" name="$accept" usefulness="useful"/>
+      <nonterminal symbol-number="9" name="$accept" type="" usefulness="useful"/>
-      <nonterminal symbol-number="10" name="unit" usefulness="useful"/>
+      <nonterminal symbol-number="10" name="unit" type="" usefulness="useful"/>
-      <nonterminal symbol-number="11" name="assignments" usefulness="useful"/>
+      <nonterminal symbol-number="11" name="assignments" type="" usefulness="useful"/>
-      <nonterminal symbol-number="12" name="assignment" usefulness="useful"/>
+      <nonterminal symbol-number="12" name="assignment" type="" usefulness="useful"/>
-      <nonterminal symbol-number="13" name="id" usefulness="useful"/>
+      <nonterminal symbol-number="13" name="id" type="std::string" usefulness="useful"/>
-      <nonterminal symbol-number="14" name="exp" usefulness="useful"/>
+      <nonterminal symbol-number="14" name="exp" type="int" usefulness="useful"/>
-      <nonterminal symbol-number="15" name="@1" usefulness="useful"/>
+      <nonterminal symbol-number="15" name="@1" type="int" usefulness="useful"/>
-      <nonterminal symbol-number="16" name="@2" usefulness="useful"/>
+      <nonterminal symbol-number="16" name="@2" type="int" usefulness="useful"/>
     </nonterminals>
   </grammar>
 
@@ -1137,6 +1137,373 @@ AT_CHECK([[sed -e 's/bison-xml-report version="[^"]*"/bison-xml-report version="
 </bison-xml-report>
 ]])
 
+# Check HTML output.
+if test x"$XSLTPROC" != x""; then
+  AT_CHECK([[$XSLTPROC \
+           `]]AT_SET_ENV[[ bison --print-datadir`/xslt/xml2xhtml.xsl \
+           input.xml | \
+           sed -e 's/GNU Bison [0-9][-.0-9a-z]*/GNU Bison VERSION/' \
+           >input.html]])
+
+  AT_CHECK([cat input.html], [],
+[[<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml" xmlns:bison="http://www.gnu.org/software/bison/">
+  <head>
+    <meta http-equiv="Content-Type" content="text/html;charset=UTF-8" />
+    <title>input.yy - GNU Bison XML Automaton Report</title>
+    <style type="text/css">
+      body {
+        font-family: "Nimbus Sans L", Arial, sans-serif;
+        font-size: 9pt;
+      }
+      a:link {
+        color: #1f00ff;
+        text-decoration: none;
+      }
+      a:visited {
+        color: #1f00ff;
+        text-decoration: none;
+      }
+      a:hover {
+        color: red;
+      }
+      #menu a {
+        text-decoration: underline;
+      }
+      .i {
+        font-style: italic;
+      }
+      .pre {
+        font-family: monospace;
+        white-space: pre;
+      }
+      ol.decimal {
+        list-style-type: decimal;
+      }
+      ol.lower-alpha {
+        list-style-type: lower-alpha;
+      }
+      .dot {
+        color: #cc0000;
+      }
+      #footer {
+        margin-top: 3.5em;
+        font-size: 7pt;
+      }
+      </style>
+  </head>
+  <body><h1>GNU Bison XML Automaton Report</h1><p>
+    input grammar: <span class="i">input.yy</span></p>
+
+<h3>Table of Contents</h3><ul id="menu"><li><a href="#reductions">Reductions</a><ul class="lower-alpha"><li><a href="#nonterminals_useless_in_grammar">Nonterminals useless in grammar</a></li><li><a href="#terminals_unused_in_grammar">Terminals unused in grammar</a></li><li><a href="#rules_useless_in_grammar">Rules useless in grammar</a></li></ul></li><li><a href="#conflicts">Conflicts</a></li><li><a href="#grammar">Grammar</a><ul class="lower-alpha"><li><a href="#grammar">Itemset</a></li><li><a href="#terminals">Terminal symbols</a></li><li><a href="#nonterminals">Nonterminal symbols</a></li></ul></li><li><a href="#automaton">Automaton</a></li></ul><h2><a name="reductions" id="reductions"></a> Reductions</h2><h3><a name="nonterminals_useless_in_grammar" id="nonterminals_useless_in_grammar"></a> Nonterminals useless in grammar</h3>
+
+<h3><a name="terminals_unused_in_grammar" id="terminals_unused_in_grammar"></a> Terminals unused in grammar</h3>
+
+<h3><a name="rules_useless_in_grammar" id="rules_useless_in_grammar"></a> Rules useless in grammar</h3>
+<h2><a name="conflicts" id="conflicts"></a> Conflicts</h2>
+
+<h2><a name="grammar" id="grammar"></a> Grammar</h2>
+<p class="pre">
+  <a name="rule_0" id="rule_0">  0</a> <span class="i">$accept</span> → <span class="i">unit</span> <b>"end of file"</b>
+
+  <a name="rule_1" id="rule_1">  1</a> <span class="i">unit</span> → <span class="i">assignments</span> <span class="i">exp</span>
+
+  <a name="rule_2" id="rule_2">  2</a> <span class="i">assignments</span> → %empty
+  <a name="rule_3" id="rule_3">  3</a>             | <span class="i">assignments</span> <span class="i">assignment</span>
+
+  <a name="rule_4" id="rule_4">  4</a> <span class="i">assignment</span> → <span class="i">id</span> <b>":="</b> <span class="i">exp</span>
+
+  <a name="rule_5" id="rule_5">  5</a> <span class="i">id</span> → <b>"identifier"</b>
+
+  <a name="rule_6" id="rule_6">  6</a> <span class="i">@1</span> → %empty
+
+  <a name="rule_7" id="rule_7">  7</a> <span class="i">@2</span> → %empty
+
+  <a name="rule_8" id="rule_8">  8</a> <span class="i">exp</span> → <b>"incr"</b> <span class="i">exp</span> <span class="i">@1</span> <span class="i">@2</span> <span class="i">exp</span>
+  <a name="rule_9" id="rule_9">  9</a>     | <b>"("</b> <span class="i">exp</span> <b>")"</b>
+  <a name="rule_10" id="rule_10"> 10</a>     | <b>"identifier"</b>
+  <a name="rule_11" id="rule_11"> 11</a>     | <b>"number"</b>
+</p>
+
+<h3><a name="terminals" id="terminals"></a> Terminals, with rules where they appear</h3>
+
+<ul>
+  <li><b>"end of file"</b> (0) <a href="#rule_0">0</a></li>
+  <li><b>error</b> (256)</li>
+  <li><b>":="</b> (258) <a href="#rule_4">4</a></li>
+  <li><b>"incr"</b> (259) <a href="#rule_8">8</a></li>
+  <li><b>"identifier"</b> &lt;std::string&gt; (260) <a href="#rule_5">5</a> <a href="#rule_10">10</a></li>
+  <li><b>"number"</b> &lt;int&gt; (261) <a href="#rule_11">11</a></li>
+  <li><b>"("</b> (262) <a href="#rule_9">9</a></li>
+  <li><b>")"</b> (263) <a href="#rule_9">9</a></li>
+</ul>
+
+<h3><a name="nonterminals" id="nonterminals"></a> Nonterminals, with rules where they appear</h3>
+
+<ul>
+  <li><b>$accept</b> (9)
+    <ul>
+      <li>on left: <a href="#rule_0">0</a></li>
+    </ul>
+  </li>
+  <li><b>unit</b> (10)
+    <ul>
+      <li>on left: <a href="#rule_1">1</a></li>
+      <li>on right: <a href="#rule_0">0</a></li>
+    </ul>
+  </li>
+  <li><b>assignments</b> (11)
+    <ul>
+      <li>on left: <a href="#rule_2">2</a> <a href="#rule_3">3</a></li>
+      <li>on right: <a href="#rule_1">1</a> <a href="#rule_3">3</a></li>
+    </ul>
+  </li>
+  <li><b>assignment</b> (12)
+    <ul>
+      <li>on left: <a href="#rule_4">4</a></li>
+      <li>on right: <a href="#rule_3">3</a></li>
+    </ul>
+  </li>
+  <li><b>id</b> &lt;std::string&gt; (13)
+    <ul>
+      <li>on left: <a href="#rule_5">5</a></li>
+      <li>on right: <a href="#rule_4">4</a></li>
+    </ul>
+  </li>
+  <li><b>exp</b> &lt;int&gt; (14)
+    <ul>
+      <li>on left: <a href="#rule_8">8</a> <a href="#rule_9">9</a> <a href="#rule_10">10</a> <a href="#rule_11">11</a></li>
+      <li>on right: <a href="#rule_1">1</a> <a href="#rule_4">4</a> <a href="#rule_8">8</a> <a href="#rule_9">9</a></li>
+    </ul>
+  </li>
+  <li><b>@1</b> &lt;int&gt; (15)
+    <ul>
+      <li>on left: <a href="#rule_6">6</a></li>
+      <li>on right: <a href="#rule_8">8</a></li>
+    </ul>
+  </li>
+  <li><b>@2</b> &lt;int&gt; (16)
+    <ul>
+      <li>on left: <a href="#rule_7">7</a></li>
+      <li>on right: <a href="#rule_8">8</a></li>
+    </ul>
+  </li>
+</ul><h2><a name="automaton" id="automaton"></a> Automaton</h2>
+
+<h3><a name="state_0" id="state_0"></a>State 0</h3>
+
+<p class="pre">  <a href="#rule_0">  0</a> <span class="i">$accept</span> → <span class="dot">•</span> <span class="i">unit</span> <b>"end of file"</b>
+  <a href="#rule_1">  1</a> <span class="i">unit</span> → <span class="dot">•</span> <span class="i">assignments</span> <span class="i">exp</span>
+  <a href="#rule_2">  2</a> <span class="i">assignments</span> → <span class="dot">•</span> %empty
+  <a href="#rule_3">  3</a>             | <span class="dot">•</span> <span class="i">assignments</span> <span class="i">assignment</span>
+
+    $default  <a href="#rule_2">reduce using rule 2</a> (assignments)
+
+    unit         <a href="#state_1">go to state 1</a>
+    assignments  <a href="#state_2">go to state 2</a>
+</p>
+
+<h3><a name="state_1" id="state_1"></a>State 1</h3>
+
+<p class="pre">  <a href="#rule_0">  0</a> <span class="i">$accept</span> → <span class="i">unit</span> <span class="dot">•</span> <b>"end of file"</b>
+
+    "end of file"  <a href="#state_3">shift, and go to state 3</a>
+</p>
+
+<h3><a name="state_2" id="state_2"></a>State 2</h3>
+
+<p class="pre">  <a href="#rule_1">  1</a> <span class="i">unit</span> → <span class="i">assignments</span> <span class="dot">•</span> <span class="i">exp</span>
+  <a href="#rule_3">  3</a> <span class="i">assignments</span> → <span class="i">assignments</span> <span class="dot">•</span> <span class="i">assignment</span>
+  <a href="#rule_4">  4</a> <span class="i">assignment</span> → <span class="dot">•</span> <span class="i">id</span> <b>":="</b> <span class="i">exp</span>
+  <a href="#rule_5">  5</a> <span class="i">id</span> → <span class="dot">•</span> <b>"identifier"</b>
+  <a href="#rule_8">  8</a> <span class="i">exp</span> → <span class="dot">•</span> <b>"incr"</b> <span class="i">exp</span> <span class="i">@1</span> <span class="i">@2</span> <span class="i">exp</span>
+  <a href="#rule_9">  9</a>     | <span class="dot">•</span> <b>"("</b> <span class="i">exp</span> <b>")"</b>
+  <a href="#rule_10"> 10</a>     | <span class="dot">•</span> <b>"identifier"</b>
+  <a href="#rule_11"> 11</a>     | <span class="dot">•</span> <b>"number"</b>
+
+    "incr"        <a href="#state_4">shift, and go to state 4</a>
+    "identifier"  <a href="#state_5">shift, and go to state 5</a>
+    "number"      <a href="#state_6">shift, and go to state 6</a>
+    "("           <a href="#state_7">shift, and go to state 7</a>
+
+    assignment  <a href="#state_8">go to state 8</a>
+    id          <a href="#state_9">go to state 9</a>
+    exp         <a href="#state_10">go to state 10</a>
+</p>
+
+<h3><a name="state_3" id="state_3"></a>State 3</h3>
+
+<p class="pre">  <a href="#rule_0">  0</a> <span class="i">$accept</span> → <span class="i">unit</span> <b>"end of file"</b> <span class="dot">•</span>
+
+    $default  accept
+</p>
+
+<h3><a name="state_4" id="state_4"></a>State 4</h3>
+
+<p class="pre">  <a href="#rule_8">  8</a> <span class="i">exp</span> → <span class="dot">•</span> <b>"incr"</b> <span class="i">exp</span> <span class="i">@1</span> <span class="i">@2</span> <span class="i">exp</span>
+  <a href="#rule_8">  8</a>     | <b>"incr"</b> <span class="dot">•</span> <span class="i">exp</span> <span class="i">@1</span> <span class="i">@2</span> <span class="i">exp</span>
+  <a href="#rule_9">  9</a>     | <span class="dot">•</span> <b>"("</b> <span class="i">exp</span> <b>")"</b>
+  <a href="#rule_10"> 10</a>     | <span class="dot">•</span> <b>"identifier"</b>
+  <a href="#rule_11"> 11</a>     | <span class="dot">•</span> <b>"number"</b>
+
+    "incr"        <a href="#state_4">shift, and go to state 4</a>
+    "identifier"  <a href="#state_11">shift, and go to state 11</a>
+    "number"      <a href="#state_6">shift, and go to state 6</a>
+    "("           <a href="#state_7">shift, and go to state 7</a>
+
+    exp  <a href="#state_12">go to state 12</a>
+</p>
+
+<h3><a name="state_5" id="state_5"></a>State 5</h3>
+
+<p class="pre">  <a href="#rule_5">  5</a> <span class="i">id</span> → <b>"identifier"</b> <span class="dot">•</span>  [":="]
+  <a href="#rule_10"> 10</a> <span class="i">exp</span> → <b>"identifier"</b> <span class="dot">•</span>  ["end of file"]
+
+    "end of file"  <a href="#rule_10">reduce using rule 10</a> (exp)
+    $default       <a href="#rule_5">reduce using rule 5</a> (id)
+</p>
+
+<h3><a name="state_6" id="state_6"></a>State 6</h3>
+
+<p class="pre">  <a href="#rule_11"> 11</a> <span class="i">exp</span> → <b>"number"</b> <span class="dot">•</span>
+
+    $default  <a href="#rule_11">reduce using rule 11</a> (exp)
+</p>
+
+<h3><a name="state_7" id="state_7"></a>State 7</h3>
+
+<p class="pre">  <a href="#rule_8">  8</a> <span class="i">exp</span> → <span class="dot">•</span> <b>"incr"</b> <span class="i">exp</span> <span class="i">@1</span> <span class="i">@2</span> <span class="i">exp</span>
+  <a href="#rule_9">  9</a>     | <span class="dot">•</span> <b>"("</b> <span class="i">exp</span> <b>")"</b>
+  <a href="#rule_9">  9</a>     | <b>"("</b> <span class="dot">•</span> <span class="i">exp</span> <b>")"</b>
+  <a href="#rule_10"> 10</a>     | <span class="dot">•</span> <b>"identifier"</b>
+  <a href="#rule_11"> 11</a>     | <span class="dot">•</span> <b>"number"</b>
+
+    "incr"        <a href="#state_4">shift, and go to state 4</a>
+    "identifier"  <a href="#state_11">shift, and go to state 11</a>
+    "number"      <a href="#state_6">shift, and go to state 6</a>
+    "("           <a href="#state_7">shift, and go to state 7</a>
+
+    exp  <a href="#state_13">go to state 13</a>
+</p>
+
+<h3><a name="state_8" id="state_8"></a>State 8</h3>
+
+<p class="pre">  <a href="#rule_3">  3</a> <span class="i">assignments</span> → <span class="i">assignments</span> <span class="i">assignment</span> <span class="dot">•</span>
+
+    $default  <a href="#rule_3">reduce using rule 3</a> (assignments)
+</p>
+
+<h3><a name="state_9" id="state_9"></a>State 9</h3>
+
+<p class="pre">  <a href="#rule_4">  4</a> <span class="i">assignment</span> → <span class="i">id</span> <span class="dot">•</span> <b>":="</b> <span class="i">exp</span>
+
+    ":="  <a href="#state_14">shift, and go to state 14</a>
+</p>
+
+<h3><a name="state_10" id="state_10"></a>State 10</h3>
+
+<p class="pre">  <a href="#rule_1">  1</a> <span class="i">unit</span> → <span class="i">assignments</span> <span class="i">exp</span> <span class="dot">•</span>
+
+    $default  <a href="#rule_1">reduce using rule 1</a> (unit)
+</p>
+
+<h3><a name="state_11" id="state_11"></a>State 11</h3>
+
+<p class="pre">  <a href="#rule_10"> 10</a> <span class="i">exp</span> → <b>"identifier"</b> <span class="dot">•</span>
+
+    $default  <a href="#rule_10">reduce using rule 10</a> (exp)
+</p>
+
+<h3><a name="state_12" id="state_12"></a>State 12</h3>
+
+<p class="pre">  <a href="#rule_6">  6</a> <span class="i">@1</span> → <span class="dot">•</span> %empty
+  <a href="#rule_8">  8</a> <span class="i">exp</span> → <b>"incr"</b> <span class="i">exp</span> <span class="dot">•</span> <span class="i">@1</span> <span class="i">@2</span> <span class="i">exp</span>
+
+    $default  <a href="#rule_6">reduce using rule 6</a> (@1)
+
+    @1  <a href="#state_15">go to state 15</a>
+</p>
+
+<h3><a name="state_13" id="state_13"></a>State 13</h3>
+
+<p class="pre">  <a href="#rule_9">  9</a> <span class="i">exp</span> → <b>"("</b> <span class="i">exp</span> <span class="dot">•</span> <b>")"</b>
+
+    ")"  <a href="#state_16">shift, and go to state 16</a>
+</p>
+
+<h3><a name="state_14" id="state_14"></a>State 14</h3>
+
+<p class="pre">  <a href="#rule_4">  4</a> <span class="i">assignment</span> → <span class="i">id</span> <b>":="</b> <span class="dot">•</span> <span class="i">exp</span>
+  <a href="#rule_8">  8</a> <span class="i">exp</span> → <span class="dot">•</span> <b>"incr"</b> <span class="i">exp</span> <span class="i">@1</span> <span class="i">@2</span> <span class="i">exp</span>
+  <a href="#rule_9">  9</a>     | <span class="dot">•</span> <b>"("</b> <span class="i">exp</span> <b>")"</b>
+  <a href="#rule_10"> 10</a>     | <span class="dot">•</span> <b>"identifier"</b>
+  <a href="#rule_11"> 11</a>     | <span class="dot">•</span> <b>"number"</b>
+
+    "incr"        <a href="#state_4">shift, and go to state 4</a>
+    "identifier"  <a href="#state_11">shift, and go to state 11</a>
+    "number"      <a href="#state_6">shift, and go to state 6</a>
+    "("           <a href="#state_7">shift, and go to state 7</a>
+
+    exp  <a href="#state_17">go to state 17</a>
+</p>
+
+<h3><a name="state_15" id="state_15"></a>State 15</h3>
+
+<p class="pre">  <a href="#rule_7">  7</a> <span class="i">@2</span> → <span class="dot">•</span> %empty
+  <a href="#rule_8">  8</a> <span class="i">exp</span> → <b>"incr"</b> <span class="i">exp</span> <span class="i">@1</span> <span class="dot">•</span> <span class="i">@2</span> <span class="i">exp</span>
+
+    $default  <a href="#rule_7">reduce using rule 7</a> (@2)
+
+    @2  <a href="#state_18">go to state 18</a>
+</p>
+
+<h3><a name="state_16" id="state_16"></a>State 16</h3>
+
+<p class="pre">  <a href="#rule_9">  9</a> <span class="i">exp</span> → <b>"("</b> <span class="i">exp</span> <b>")"</b> <span class="dot">•</span>
+
+    $default  <a href="#rule_9">reduce using rule 9</a> (exp)
+</p>
+
+<h3><a name="state_17" id="state_17"></a>State 17</h3>
+
+<p class="pre">  <a href="#rule_4">  4</a> <span class="i">assignment</span> → <span class="i">id</span> <b>":="</b> <span class="i">exp</span> <span class="dot">•</span>
+
+    $default  <a href="#rule_4">reduce using rule 4</a> (assignment)
+</p>
+
+<h3><a name="state_18" id="state_18"></a>State 18</h3>
+
+<p class="pre">  <a href="#rule_8">  8</a> <span class="i">exp</span> → <span class="dot">•</span> <b>"incr"</b> <span class="i">exp</span> <span class="i">@1</span> <span class="i">@2</span> <span class="i">exp</span>
+  <a href="#rule_8">  8</a>     | <b>"incr"</b> <span class="i">exp</span> <span class="i">@1</span> <span class="i">@2</span> <span class="dot">•</span> <span class="i">exp</span>
+  <a href="#rule_9">  9</a>     | <span class="dot">•</span> <b>"("</b> <span class="i">exp</span> <b>")"</b>
+  <a href="#rule_10"> 10</a>     | <span class="dot">•</span> <b>"identifier"</b>
+  <a href="#rule_11"> 11</a>     | <span class="dot">•</span> <b>"number"</b>
+
+    "incr"        <a href="#state_4">shift, and go to state 4</a>
+    "identifier"  <a href="#state_11">shift, and go to state 11</a>
+    "number"      <a href="#state_6">shift, and go to state 6</a>
+    "("           <a href="#state_7">shift, and go to state 7</a>
+
+    exp  <a href="#state_19">go to state 19</a>
+</p>
+
+<h3><a name="state_19" id="state_19"></a>State 19</h3>
+
+<p class="pre">  <a href="#rule_8">  8</a> <span class="i">exp</span> → <b>"incr"</b> <span class="i">exp</span> <span class="i">@1</span> <span class="i">@2</span> <span class="i">exp</span> <span class="dot">•</span>
+
+    $default  <a href="#rule_8">reduce using rule 8</a> (exp)
+</p>
+
+<div id="footer"><hr />This document was generated using
+      <a href="http://www.gnu.org/software/bison/" title="GNU Bison">
+      GNU Bison VERSION</a>
+      XML Automaton Report.<br />
+      Verbatim copying and distribution of this entire page is
+      permitted in any medium, provided this notice is preserved.</div></body>
+</html>
+]])
+fi
 
 AT_BISON_OPTION_POPDEFS
 AT_CLEANUP
@@ -1170,41 +1537,70 @@ exp
 AT_CHECK([LC_ALL="$locale" bison -fno-caret -o input.cc -rall -Wcex --graph=input.gv --xml input.y], [], [],
 [[input.y: warning: 3 shift/reduce conflicts [-Wconflicts-sr]
 input.y: warning: 3 reduce/reduce conflicts [-Wconflicts-rr]
-Shift/reduce conflict on token "⊕":
+input.y: warning: shift/reduce conflict on token "⊕" [-Wcounterexamples]
-  Example              exp "+" exp • "⊕" exp
+  Example: exp "+" exp • "⊕" exp
-  First derivation     exp ::=[ exp ::=[ exp "+" exp • ] "⊕" exp ]
+  Shift derivation
-  Second derivation    exp ::=[ exp "+" exp ::=[ exp • "⊕" exp ] ]
+    exp
-
+    ↳ exp "+" exp
-Reduce/reduce conflict on tokens $end, "+", "⊕":
+              ↳ exp • "⊕" exp
-  Example              exp "+" exp •
+  Reduce derivation
-  First derivation     exp ::=[ exp "+" exp • ]
+    exp
-  Second derivation    exp ::=[ exp "+" exp • ]
+    ↳ exp             "⊕" exp
-
+      ↳ exp "+" exp •
-Shift/reduce conflict on token "⊕":
+input.y: warning: reduce/reduce conflict on tokens $end, "+", "⊕" [-Wcounterexamples]
-  Example              exp "+" exp • "⊕" exp
+  Example: exp "+" exp •
-  First derivation     exp ::=[ exp ::=[ exp "+" exp • ] "⊕" exp ]
+  First reduce derivation
-  Second derivation    exp ::=[ exp "+" exp ::=[ exp • "⊕" exp ] ]
+    exp
-
+    ↳ exp "+" exp •
-Shift/reduce conflict on token "⊕":
+  Second reduce derivation
-  Example              exp "⊕" exp • "⊕" exp
+    exp
-  First derivation     exp ::=[ exp ::=[ exp "⊕" exp • ] "⊕" exp ]
+    ↳ exp "+" exp •
-  Second derivation    exp ::=[ exp "⊕" exp ::=[ exp • "⊕" exp ] ]
+input.y: warning: shift/reduce conflict on token "⊕" [-Wcounterexamples]
-
+  Example: exp "+" exp • "⊕" exp
-Shift/reduce conflict on token "+":
+  Shift derivation
-  Example              exp "⊕" exp • "+" exp
+    exp
-  First derivation     exp ::=[ exp ::=[ exp "⊕" exp • ] "+" exp ]
+    ↳ exp "+" exp
-  Second derivation    exp ::=[ exp "⊕" exp ::=[ exp • "+" exp ] ]
+              ↳ exp • "⊕" exp
-
+  Reduce derivation
-Shift/reduce conflict on token "+":
+    exp
-  Example              exp "⊕" exp • "+" exp
+    ↳ exp             "⊕" exp
-  First derivation     exp ::=[ exp ::=[ exp "⊕" exp • ] "+" exp ]
+      ↳ exp "+" exp •
-  Second derivation    exp ::=[ exp "⊕" exp ::=[ exp • "+" exp ] ]
+input.y: warning: shift/reduce conflict on token "⊕" [-Wcounterexamples]
-
+  Example: exp "⊕" exp • "⊕" exp
+  Shift derivation
+    exp
+    ↳ exp "⊕" exp
+              ↳ exp • "⊕" exp
+  Reduce derivation
+    exp
+    ↳ exp             "⊕" exp
+      ↳ exp "⊕" exp •
+input.y: warning: shift/reduce conflict on token "+" [-Wcounterexamples]
+  Example: exp "⊕" exp • "+" exp
+  Shift derivation
+    exp
+    ↳ exp "⊕" exp
+              ↳ exp • "+" exp
+  Reduce derivation
+    exp
+    ↳ exp             "+" exp
+      ↳ exp "⊕" exp •
+input.y: warning: shift/reduce conflict on token "+" [-Wcounterexamples]
+  Example: exp "⊕" exp • "+" exp
+  Shift derivation
+    exp
+    ↳ exp "⊕" exp
+              ↳ exp • "+" exp
+  Reduce derivation
+    exp
+    ↳ exp             "+" exp
+      ↳ exp "⊕" exp •
 input.y:6.3-13: warning: rule useless in parser due to conflicts [-Wother]
 ]])
 
 # Check the contents of the report.
-AT_CHECK([cat input.output], [],
+# FIXME: Avoid trailing white spaces.
+AT_CHECK([sed -e 's/ *$//' input.output], [],
 [[Rules useless in parser due to conflicts
 
     3 exp: exp "+" exp
@@ -1343,26 +1739,42 @@ State 7
 
     Conflict between rule 2 and token "+" resolved as reduce (%left "+").
 
-    Shift/reduce conflict on token "⊕":
+    shift/reduce conflict on token "⊕":
         2 exp: exp "+" exp •
         1 exp: exp • "⊕" exp
-      Example                  exp "+" exp • "⊕" exp
+      Example: exp "+" exp • "⊕" exp
-      First derivation         exp ::=[ exp ::=[ exp "+" exp • ] "⊕" exp ]
+      Shift derivation
-      Second derivation        exp ::=[ exp "+" exp ::=[ exp • "⊕" exp ] ]
+        exp
+        ↳ exp "+" exp
+                  ↳ exp • "⊕" exp
+      Reduce derivation
+        exp
+        ↳ exp             "⊕" exp
+          ↳ exp "+" exp •
 
-    Reduce/reduce conflict on tokens $end, "+", "⊕":
+    reduce/reduce conflict on tokens $end, "+", "⊕":
         2 exp: exp "+" exp •
         3 exp: exp "+" exp •
-      Example                  exp "+" exp •
+      Example: exp "+" exp •
-      First derivation         exp ::=[ exp "+" exp • ]
+      First reduce derivation
-      Second derivation        exp ::=[ exp "+" exp • ]
+        exp
+        ↳ exp "+" exp •
+      Second reduce derivation
+        exp
+        ↳ exp "+" exp •
 
-    Shift/reduce conflict on token "⊕":
+    shift/reduce conflict on token "⊕":
         3 exp: exp "+" exp •
         1 exp: exp • "⊕" exp
-      Example                  exp "+" exp • "⊕" exp
+      Example: exp "+" exp • "⊕" exp
-      First derivation         exp ::=[ exp ::=[ exp "+" exp • ] "⊕" exp ]
+      Shift derivation
-      Second derivation        exp ::=[ exp "+" exp ::=[ exp • "⊕" exp ] ]
+        exp
+        ↳ exp "+" exp
+                  ↳ exp • "⊕" exp
+      Reduce derivation
+        exp
+        ↳ exp             "⊕" exp
+          ↳ exp "+" exp •
 
 
 
@@ -1380,26 +1792,44 @@ State 8
     "⊕"       [reduce using rule 1 (exp)]
     $default  reduce using rule 1 (exp)
 
-    Shift/reduce conflict on token "⊕":
+    shift/reduce conflict on token "⊕":
         1 exp: exp "⊕" exp •
         1 exp: exp • "⊕" exp
-      Example                  exp "⊕" exp • "⊕" exp
+      Example: exp "⊕" exp • "⊕" exp
-      First derivation         exp ::=[ exp ::=[ exp "⊕" exp • ] "⊕" exp ]
+      Shift derivation
-      Second derivation        exp ::=[ exp "⊕" exp ::=[ exp • "⊕" exp ] ]
+        exp
+        ↳ exp "⊕" exp
+                  ↳ exp • "⊕" exp
+      Reduce derivation
+        exp
+        ↳ exp             "⊕" exp
+          ↳ exp "⊕" exp •
 
-    Shift/reduce conflict on token "+":
+    shift/reduce conflict on token "+":
         1 exp: exp "⊕" exp •
         2 exp: exp • "+" exp
-      Example                  exp "⊕" exp • "+" exp
+      Example: exp "⊕" exp • "+" exp
-      First derivation         exp ::=[ exp ::=[ exp "⊕" exp • ] "+" exp ]
+      Shift derivation
-      Second derivation        exp ::=[ exp "⊕" exp ::=[ exp • "+" exp ] ]
+        exp
+        ↳ exp "⊕" exp
+                  ↳ exp • "+" exp
+      Reduce derivation
+        exp
+        ↳ exp             "+" exp
+          ↳ exp "⊕" exp •
 
-    Shift/reduce conflict on token "+":
+    shift/reduce conflict on token "+":
         1 exp: exp "⊕" exp •
         3 exp: exp • "+" exp
-      Example                  exp "⊕" exp • "+" exp
+      Example: exp "⊕" exp • "+" exp
-      First derivation         exp ::=[ exp ::=[ exp "⊕" exp • ] "+" exp ]
+      Shift derivation
-      Second derivation        exp ::=[ exp "⊕" exp ::=[ exp • "+" exp ] ]
+        exp
+        ↳ exp "⊕" exp
+                  ↳ exp • "+" exp
+      Reduce derivation
+        exp
+        ↳ exp             "+" exp
+          ↳ exp "⊕" exp •
 
 ]])
 
@@ -1514,16 +1944,16 @@ AT_CHECK([[sed -e 's/bison-xml-report version="[^"]*"/bison-xml-report version="
       </rule>
     </rules>
     <terminals>
-      <terminal symbol-number="0" token-number="0" name="$end" usefulness="useful"/>
+      <terminal symbol-number="0" token-number="0" name="$end" type="" usefulness="useful"/>
-      <terminal symbol-number="1" token-number="256" name="error" usefulness="useful"/>
+      <terminal symbol-number="1" token-number="256" name="error" type="" usefulness="useful"/>
-      <terminal symbol-number="3" token-number="258" name="&quot;+&quot;" usefulness="useful" prec="1" assoc="left"/>
+      <terminal symbol-number="3" token-number="258" name="&quot;+&quot;" type="" usefulness="useful" prec="1" assoc="left"/>
-      <terminal symbol-number="4" token-number="259" name="&quot;⊕&quot;" usefulness="useful"/>
+      <terminal symbol-number="4" token-number="259" name="&quot;⊕&quot;" type="" usefulness="useful"/>
-      <terminal symbol-number="5" token-number="260" name="&quot;number&quot;" usefulness="useful"/>
+      <terminal symbol-number="5" token-number="260" name="&quot;number&quot;" type="" usefulness="useful"/>
-      <terminal symbol-number="6" token-number="261" name="&quot;Ñùṃéℝô&quot;" usefulness="useful"/>
+      <terminal symbol-number="6" token-number="261" name="&quot;Ñùṃéℝô&quot;" type="" usefulness="useful"/>
     </terminals>
     <nonterminals>
-      <nonterminal symbol-number="7" name="$accept" usefulness="useful"/>
+      <nonterminal symbol-number="7" name="$accept" type="" usefulness="useful"/>
-      <nonterminal symbol-number="8" name="exp" usefulness="useful"/>
+      <nonterminal symbol-number="8" name="exp" type="" usefulness="useful"/>
     </nonterminals>
   </grammar>
 
@@ -1725,6 +2155,243 @@ AT_CHECK([[sed -e 's/bison-xml-report version="[^"]*"/bison-xml-report version="
 </bison-xml-report>
 ]])
 
+# Check HTML output.
+if test x"$XSLTPROC" != x""; then
+  AT_CHECK([[$XSLTPROC \
+           `]]AT_SET_ENV[[ bison --print-datadir`/xslt/xml2xhtml.xsl \
+           input.xml | \
+           sed -e 's/GNU Bison [0-9][-.0-9a-z]*/GNU Bison VERSION/' \
+           >input.html]])
+
+  AT_CHECK([cat input.html], [],
+[[<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml" xmlns:bison="http://www.gnu.org/software/bison/">
+  <head>
+    <meta http-equiv="Content-Type" content="text/html;charset=UTF-8" />
+    <title>input.y - GNU Bison XML Automaton Report</title>
+    <style type="text/css">
+      body {
+        font-family: "Nimbus Sans L", Arial, sans-serif;
+        font-size: 9pt;
+      }
+      a:link {
+        color: #1f00ff;
+        text-decoration: none;
+      }
+      a:visited {
+        color: #1f00ff;
+        text-decoration: none;
+      }
+      a:hover {
+        color: red;
+      }
+      #menu a {
+        text-decoration: underline;
+      }
+      .i {
+        font-style: italic;
+      }
+      .pre {
+        font-family: monospace;
+        white-space: pre;
+      }
+      ol.decimal {
+        list-style-type: decimal;
+      }
+      ol.lower-alpha {
+        list-style-type: lower-alpha;
+      }
+      .dot {
+        color: #cc0000;
+      }
+      #footer {
+        margin-top: 3.5em;
+        font-size: 7pt;
+      }
+      </style>
+  </head>
+  <body><h1>GNU Bison XML Automaton Report</h1><p>
+    input grammar: <span class="i">input.y</span></p>
+
+<h3>Table of Contents</h3><ul id="menu"><li><a href="#reductions">Reductions</a><ul class="lower-alpha"><li><a href="#nonterminals_useless_in_grammar">Nonterminals useless in grammar</a></li><li><a href="#terminals_unused_in_grammar">Terminals unused in grammar</a></li><li><a href="#rules_useless_in_grammar">Rules useless in grammar</a></li><li><a href="#rules_useless_in_parser">Rules useless in parser due to conflicts</a></li></ul></li><li><a href="#conflicts">Conflicts</a></li><li><a href="#grammar">Grammar</a><ul class="lower-alpha"><li><a href="#grammar">Itemset</a></li><li><a href="#terminals">Terminal symbols</a></li><li><a href="#nonterminals">Nonterminal symbols</a></li></ul></li><li><a href="#automaton">Automaton</a></li></ul><h2><a name="reductions" id="reductions"></a> Reductions</h2><h3><a name="nonterminals_useless_in_grammar" id="nonterminals_useless_in_grammar"></a> Nonterminals useless in grammar</h3>
+
+<h3><a name="terminals_unused_in_grammar" id="terminals_unused_in_grammar"></a> Terminals unused in grammar</h3>
+
+<h3><a name="rules_useless_in_grammar" id="rules_useless_in_grammar"></a> Rules useless in grammar</h3>
+<h2><a name="rules_useless_in_parser" id="rules_useless_in_parser"></a> Rules useless in parser due to conflicts</h2>
+<p class="pre">
+  <a href="#rule_3">  3</a> <span class="i">exp</span> → <span class="i">exp</span> <b>"+"</b> <span class="i">exp</span>
+</p>
+
+<h2><a name="conflicts" id="conflicts"></a> Conflicts</h2>
+
+<p class="pre"><a href="#state_7">State 7</a> conflicts: 1 shift/reduce, 3 reduce/reduce
+<a href="#state_8">State 8</a> conflicts: 2 shift/reduce
+
+
+</p><h2><a name="grammar" id="grammar"></a> Grammar</h2>
+<p class="pre">
+  <a name="rule_0" id="rule_0">  0</a> <span class="i">$accept</span> → <span class="i">exp</span> <b>$end</b>
+
+  <a name="rule_1" id="rule_1">  1</a> <span class="i">exp</span> → <span class="i">exp</span> <b>"⊕"</b> <span class="i">exp</span>
+  <a name="rule_2" id="rule_2">  2</a>     | <span class="i">exp</span> <b>"+"</b> <span class="i">exp</span>
+  <a name="rule_3" id="rule_3">  3</a>     | <span class="i">exp</span> <b>"+"</b> <span class="i">exp</span>
+  <a name="rule_4" id="rule_4">  4</a>     | <b>"number"</b>
+  <a name="rule_5" id="rule_5">  5</a>     | <b>"Ñùṃéℝô"</b>
+</p>
+
+<h3><a name="terminals" id="terminals"></a> Terminals, with rules where they appear</h3>
+
+<ul>
+  <li><b>$end</b> (0) <a href="#rule_0">0</a></li>
+  <li><b>error</b> (256)</li>
+  <li><b>"+"</b> (258) <a href="#rule_2">2</a> <a href="#rule_3">3</a></li>
+  <li><b>"⊕"</b> (259) <a href="#rule_1">1</a></li>
+  <li><b>"number"</b> (260) <a href="#rule_4">4</a></li>
+  <li><b>"Ñùṃéℝô"</b> (261) <a href="#rule_5">5</a></li>
+</ul>
+
+<h3><a name="nonterminals" id="nonterminals"></a> Nonterminals, with rules where they appear</h3>
+
+<ul>
+  <li><b>$accept</b> (7)
+    <ul>
+      <li>on left: <a href="#rule_0">0</a></li>
+    </ul>
+  </li>
+  <li><b>exp</b> (8)
+    <ul>
+      <li>on left: <a href="#rule_1">1</a> <a href="#rule_2">2</a> <a href="#rule_3">3</a> <a href="#rule_4">4</a> <a href="#rule_5">5</a></li>
+      <li>on right: <a href="#rule_0">0</a> <a href="#rule_1">1</a> <a href="#rule_2">2</a> <a href="#rule_3">3</a></li>
+    </ul>
+  </li>
+</ul><h2><a name="automaton" id="automaton"></a> Automaton</h2>
+
+<h3><a name="state_0" id="state_0"></a>State 0</h3>
+
+<p class="pre">  <a href="#rule_0">  0</a> <span class="i">$accept</span> → <span class="dot">•</span> <span class="i">exp</span> <b>$end</b>
+  <a href="#rule_1">  1</a> <span class="i">exp</span> → <span class="dot">•</span> <span class="i">exp</span> <b>"⊕"</b> <span class="i">exp</span>
+  <a href="#rule_2">  2</a>     | <span class="dot">•</span> <span class="i">exp</span> <b>"+"</b> <span class="i">exp</span>
+  <a href="#rule_3">  3</a>     | <span class="dot">•</span> <span class="i">exp</span> <b>"+"</b> <span class="i">exp</span>
+  <a href="#rule_4">  4</a>     | <span class="dot">•</span> <b>"number"</b>
+  <a href="#rule_5">  5</a>     | <span class="dot">•</span> <b>"Ñùṃéℝô"</b>
+
+    "number"  <a href="#state_1">shift, and go to state 1</a>
+    "Ñùṃéℝô"  <a href="#state_2">shift, and go to state 2</a>
+
+    exp  <a href="#state_3">go to state 3</a>
+</p>
+
+<h3><a name="state_1" id="state_1"></a>State 1</h3>
+
+<p class="pre">  <a href="#rule_4">  4</a> <span class="i">exp</span> → <b>"number"</b> <span class="dot">•</span>
+
+    $default  <a href="#rule_4">reduce using rule 4</a> (exp)
+</p>
+
+<h3><a name="state_2" id="state_2"></a>State 2</h3>
+
+<p class="pre">  <a href="#rule_5">  5</a> <span class="i">exp</span> → <b>"Ñùṃéℝô"</b> <span class="dot">•</span>
+
+    $default  <a href="#rule_5">reduce using rule 5</a> (exp)
+</p>
+
+<h3><a name="state_3" id="state_3"></a>State 3</h3>
+
+<p class="pre">  <a href="#rule_0">  0</a> <span class="i">$accept</span> → <span class="i">exp</span> <span class="dot">•</span> <b>$end</b>
+  <a href="#rule_1">  1</a> <span class="i">exp</span> → <span class="i">exp</span> <span class="dot">•</span> <b>"⊕"</b> <span class="i">exp</span>
+  <a href="#rule_2">  2</a>     | <span class="i">exp</span> <span class="dot">•</span> <b>"+"</b> <span class="i">exp</span>
+  <a href="#rule_3">  3</a>     | <span class="i">exp</span> <span class="dot">•</span> <b>"+"</b> <span class="i">exp</span>
+
+    $end  <a href="#state_4">shift, and go to state 4</a>
+    "+"   <a href="#state_5">shift, and go to state 5</a>
+    "⊕"   <a href="#state_6">shift, and go to state 6</a>
+</p>
+
+<h3><a name="state_4" id="state_4"></a>State 4</h3>
+
+<p class="pre">  <a href="#rule_0">  0</a> <span class="i">$accept</span> → <span class="i">exp</span> <b>$end</b> <span class="dot">•</span>
+
+    $default  accept
+</p>
+
+<h3><a name="state_5" id="state_5"></a>State 5</h3>
+
+<p class="pre">  <a href="#rule_1">  1</a> <span class="i">exp</span> → <span class="dot">•</span> <span class="i">exp</span> <b>"⊕"</b> <span class="i">exp</span>
+  <a href="#rule_2">  2</a>     | <span class="dot">•</span> <span class="i">exp</span> <b>"+"</b> <span class="i">exp</span>
+  <a href="#rule_2">  2</a>     | <span class="i">exp</span> <b>"+"</b> <span class="dot">•</span> <span class="i">exp</span>
+  <a href="#rule_3">  3</a>     | <span class="dot">•</span> <span class="i">exp</span> <b>"+"</b> <span class="i">exp</span>
+  <a href="#rule_3">  3</a>     | <span class="i">exp</span> <b>"+"</b> <span class="dot">•</span> <span class="i">exp</span>
+  <a href="#rule_4">  4</a>     | <span class="dot">•</span> <b>"number"</b>
+  <a href="#rule_5">  5</a>     | <span class="dot">•</span> <b>"Ñùṃéℝô"</b>
+
+    "number"  <a href="#state_1">shift, and go to state 1</a>
+    "Ñùṃéℝô"  <a href="#state_2">shift, and go to state 2</a>
+
+    exp  <a href="#state_7">go to state 7</a>
+</p>
+
+<h3><a name="state_6" id="state_6"></a>State 6</h3>
+
+<p class="pre">  <a href="#rule_1">  1</a> <span class="i">exp</span> → <span class="dot">•</span> <span class="i">exp</span> <b>"⊕"</b> <span class="i">exp</span>
+  <a href="#rule_1">  1</a>     | <span class="i">exp</span> <b>"⊕"</b> <span class="dot">•</span> <span class="i">exp</span>
+  <a href="#rule_2">  2</a>     | <span class="dot">•</span> <span class="i">exp</span> <b>"+"</b> <span class="i">exp</span>
+  <a href="#rule_3">  3</a>     | <span class="dot">•</span> <span class="i">exp</span> <b>"+"</b> <span class="i">exp</span>
+  <a href="#rule_4">  4</a>     | <span class="dot">•</span> <b>"number"</b>
+  <a href="#rule_5">  5</a>     | <span class="dot">•</span> <b>"Ñùṃéℝô"</b>
+
+    "number"  <a href="#state_1">shift, and go to state 1</a>
+    "Ñùṃéℝô"  <a href="#state_2">shift, and go to state 2</a>
+
+    exp  <a href="#state_8">go to state 8</a>
+</p>
+
+<h3><a name="state_7" id="state_7"></a>State 7</h3>
+
+<p class="pre">  <a href="#rule_1">  1</a> <span class="i">exp</span> → <span class="i">exp</span> <span class="dot">•</span> <b>"⊕"</b> <span class="i">exp</span>
+  <a href="#rule_2">  2</a>     | <span class="i">exp</span> <span class="dot">•</span> <b>"+"</b> <span class="i">exp</span>
+  <a href="#rule_2">  2</a>     | <span class="i">exp</span> <b>"+"</b> <span class="i">exp</span> <span class="dot">•</span>  [$end, "+", "⊕"]
+  <a href="#rule_3">  3</a>     | <span class="i">exp</span> <span class="dot">•</span> <b>"+"</b> <span class="i">exp</span>
+  <a href="#rule_3">  3</a>     | <span class="i">exp</span> <b>"+"</b> <span class="i">exp</span> <span class="dot">•</span>  [$end, "+", "⊕"]
+
+    "⊕"  <a href="#state_6">shift, and go to state 6</a>
+
+    $end      <a href="#rule_2">reduce using rule 2</a> (exp)
+    $end      [<a href="#rule_3">reduce using rule 3</a> (exp)]
+    "+"       <a href="#rule_2">reduce using rule 2</a> (exp)
+    "+"       [<a href="#rule_3">reduce using rule 3</a> (exp)]
+    "⊕"       [<a href="#rule_2">reduce using rule 2</a> (exp)]
+    "⊕"       [<a href="#rule_3">reduce using rule 3</a> (exp)]
+    $default  <a href="#rule_2">reduce using rule 2</a> (exp)
+
+    Conflict between <a href="#rule_2">rule 2</a> and token "+" resolved as reduce (%left "+").
+</p>
+
+<h3><a name="state_8" id="state_8"></a>State 8</h3>
+
+<p class="pre">  <a href="#rule_1">  1</a> <span class="i">exp</span> → <span class="i">exp</span> <span class="dot">•</span> <b>"⊕"</b> <span class="i">exp</span>
+  <a href="#rule_1">  1</a>     | <span class="i">exp</span> <b>"⊕"</b> <span class="i">exp</span> <span class="dot">•</span>  [$end, "+", "⊕"]
+  <a href="#rule_2">  2</a>     | <span class="i">exp</span> <span class="dot">•</span> <b>"+"</b> <span class="i">exp</span>
+  <a href="#rule_3">  3</a>     | <span class="i">exp</span> <span class="dot">•</span> <b>"+"</b> <span class="i">exp</span>
+
+    "+"  <a href="#state_5">shift, and go to state 5</a>
+    "⊕"  <a href="#state_6">shift, and go to state 6</a>
+
+    "+"       [<a href="#rule_1">reduce using rule 1</a> (exp)]
+    "⊕"       [<a href="#rule_1">reduce using rule 1</a> (exp)]
+    $default  <a href="#rule_1">reduce using rule 1</a> (exp)
+</p>
+
+<div id="footer"><hr />This document was generated using
+      <a href="http://www.gnu.org/software/bison/" title="GNU Bison">
+      GNU Bison VERSION</a>
+      XML Automaton Report.<br />
+      Verbatim copying and distribution of this entire page is
+      permitted in any medium, provided this notice is preserved.</div></body>
+</html>
+]])
+fi
 
 AT_BISON_OPTION_POPDEFS
 AT_CLEANUP

tests/sets.at

@@ -285,7 +285,7 @@ term: 'n'
 
 AT_BISON_CHECK([[-fcaret input.y]], [], [],
 [[input.y: warning: 5 reduce/reduce conflicts [-Wconflicts-rr]
-input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
+input.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
 input.y:2.14-17: warning: rule useless in parser due to conflicts [-Wother]
     2 | expr: term | term | term | term | term | term
       |              ^~~~

tests/torture.at

@@ -283,11 +283,11 @@ m4_popdef([AT_TEST])
 ## Many lookahead tokens.   ##
 ## ------------------------ ##
 
-# AT_DATA_LOOKAHEAD_TOKENS_GRAMMAR(FILE-NAME, SIZE)
+# AT_DATA_LOOKAHEADS_GRAMMAR(FILE-NAME, SIZE)
-# --------------------------------------------------
+# -------------------------------------------
 # Create FILE-NAME, containing a self checking parser for a grammar
 # requiring SIZE lookahead tokens.
-m4_define([AT_DATA_LOOKAHEAD_TOKENS_GRAMMAR],
+m4_define([AT_DATA_LOOKAHEADS_GRAMMAR],
 [AT_BISON_OPTION_PUSHDEFS
 AT_DATA([[gengram.pl]],
 [[#! /usr/bin/perl -w
@@ -384,7 +384,7 @@ AT_BISON_OPTION_POPDEFS
 
 AT_SETUP([Many lookahead tokens])
 
-AT_DATA_LOOKAHEAD_TOKENS_GRAMMAR([input.y], [1000])
+AT_DATA_LOOKAHEADS_GRAMMAR([input.y], [1000])
 
 # GNU m4 requires about 70 MiB for this test on a 32-bit host.
 # Ask for 200 MiB, which should be plenty even on a 64-bit host.